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How To Set Up a Linksys SPA3102 VOIP Router/ATA for BT UK

Got a BT line? Want to make cheap calls over the Internet but don't want to buy separate phones, don't want to use a headset and don't want to have to leave your PC switched on? Want to use your normal household phones to make VOIP calls whilst still receiving incoming calls on your normal BT number?

This is a fairly comprehensive HOWTO for the Linksys/Cisco SPA3102 and a British Telecom line in a domestic situation. It also has specific configuration details for WebCallDirect.com , but will work with any VOIP SIP provider.

If you currently spend more than 20 quid a month on calls on your BT bill, then I expect this setup to pay back the £45 cost of the SPA3102 in less than 3 months. Furthermore, after a year or so, I got begging letters from BT asking me to bring back my calls to them, offering me discount packages that were still nowhere near as cheap as VOIP.

Assumptions

  • You have a Linksys/Cisco SPA3102 VOIP router / analogue telephone adaptor. Many of these tips also apply to the SPA3000.
  • You have a BT telephone line (British Telecom landline) with a master socket. It doesn't matter if your actual phone service is provided by someone else such as your ISP, the main consideration is that you have a BT-compatible master socket with an 01 or 02 telephone number. For the purpose of this document we will consider your provider to be BT.
  • You have extension wiring for your handsets that terminates with a BT plug currently plugged into the BT master wall socket, OR, you have only one handset (or DECT cordless base station) and it has a BT plug which is currently plugged into the BT master wall socket.
  • You have a landline number starting 01 or 02 (eg. 020 London, 01242 Cheltenham etc.)
  • You wish to continue receiving incoming calls on your BT landline number.
  • You wish to make all outbound charged calls using VOIP (eg. local numbers, 01 and 02 national numbers, 0845 local numbers, 07 mobile numbers, 00 international numbers etc.)
  • You wish to continue to make all free calls using BT (eg. 100 Operator, 151 Faults, 999 Emergency, 0800 freephone)
  • You have a Cat5/RJ45 wired network with broadband internet in your house. At minimum you have an existing, working, separate broadband router with a spare RJ45 LAN socket.
  • You have a computer (MS-Windows, Mac, Linux, whatever) with a web browser (Internet Explorer, Safari, Firefox, whatever) connected to the LAN.
  • You know how to change the IP address and netmask of your computer.
  • You know what the subnet, netmask, gateway and domain name servers of your LAN are, and you know a spare static IP address which you can assign to your SPA3102.
  • You have someone in your household who 1) runs up huge phone bills and 2) insists on using normal BT telephones.

Our goal is to vastly reduce the phone bill whilst the spouse/teenage children/housemate remains almost oblivious to the fact we're routing outbound calls over the Internet. In essence, save money and minimise nagging. At this point I would like to remind all readers that I love my wife Melissa very, very much.

You will also need

  • A mobile phone, so you can ring yourself to test things.
  • A credit or debit card, with which to buy some initial credit on a VOIP account, for making phonecalls.
  • A length of network cable (straight through) such that you can plug in your SPA3102 into both the network and the BT master wall socket at the same time.
  • EITHER a network switch (your broadband router may also be a switch) OR a length of CROSSOVER network cable, so you can connect to the SPA3102 using your computer.
  • EITHER a known-good RJ11 plug to BT plug cable (eg. from an old modem) OR an RJ11 socket to BT plug adaptor, eg. Maplins code AR34M. You can use the RJ11-BT adaptor to convert the RJ11 cable that came with your SPA3102. Note that RJ11 is a different size from RJ45. If you are using an old modem lead, be aware that some are 2-wires straight through (may work), some 4-wires straight through (will work) and some 2-wires crossed over (rare, but will not work).
  • An RJ11 plug to BT master socket adaptor with ring capacitor, eg. Maplins code VD36P. Note that this is NOT a "secondary adaptor" (that has no capacitor, so you won't hear the phone ring), nor is it an RJ45 BT master (RJ11 is not RJ45).

The capacitor is important. It stores a small amount of charge which is released in two short bursts to create a ring-ring sound. Originally, this burst was enough to cause an electric motor, or a lever attached to an electromagnet, to strike a bell. UK BT telephone lines have remained with this system, and BT compatible telephones will not ring unless they receive this burst of charge- even though their ring is electronic rather than a motorised bell! Your BT master wall socket contains a capacitor, but the effect of this is lost when you go through the SPA3102, because your phones are no longer directly connected to the master socket at the wall- the SPA3102 is a little telephone exhange in its own right! So you have to add a capacitor between the SPA3102 and your BT handsets in order for them to ring. Without the capacitor, you can still make and receive calls, but the phones will never ring.

Note the difference between the "BT master wall socket" (the place where the phoneline comes in to your house) and the "BT master socket adaptor" (a short wire with an RJ11 plug at one end and a BT socket with a capacitor in it at the other).

Wiring Up the Telephone Connections

  • Do not connect the SPA3102 to the mains yet. We are going to do this bit with it turned off.
  • Unplug your phones/extension wiring from your BT master wall socket (the first BT wall socket where the telephone line first enters your house).
  • Connect your SPA3102's LINE socket to your BT master wall socket, using either a known-good RJ11-BT cable (eg. an old modem cable) OR using the supplied RJ11-RJ11 cable plus an RJ11-BT adaptor (eg. Maplins code AR34M).
  • Plug the master socket adaptor (eg. Maplins code VD36P) into the SPA3102's PHONE socket. You should now have a BT socket hanging off your SPA3102.
  • Plug your BT phone(s) into the master socket adaptor.
  • Check to make sure your SPA3102 is turned off (unplugged from the mains). When turned off, the SPA3102 connects the LINE to the PHONE socket directly, and we are going to test this connection.
  • Lift the phone handset. You should hear a dial tone. Try calling a telephone number, such as your mobile or 0800 144 144 (BT chargecard automated service). If this doesn't work, your cabling is wrong.
  • Use a mobile phone to ring your normal home landline number. Your landline phone should ring as normal. If this doesn't work, most likely you are using a secondary adaptor (no ring capacitor) instead of a master adaptor (with ring capacitor). If you're desperate, you can use a spare ADSL filter to convert a secondary adaptor into a master adaptor.
  • Pick up the ringing phone and talk to yourself. If this doesn't work, your cabling is wrong. Due to echo cancellation on modern BT exchanges, you may have to tap the receiver or do some heavy breathing (ooh-er) in order to hear yourself.

Do not proceed any further until you are certain that your phone cabling is correct.

The next sections talk about configuring your SPA3102 settings. Until this is fully completed, which may take about half an hour, you won't be able to make or receive calls through the SPA3102 in the manner you'd normally expect. Therefore:

  • If you have a spouse, children, housemates or anyone else likely to want to make or receive landline phonecalls for the next half hour or so, disconnect your SPA3102 from the master socket, extensions and phones. Plug your normal phones back into the BT master wall socket as if you didn't have an SPA3102. Check that you can ring in and get a dial tone as normal.

Set the SPA3102's Web Server to Listen on the WAN Side

Linksys assume that you will be using the SPA3102 as both a VOIP router and a network router. I am going to assume this is not the case for your domestic situation. I am going to assume that you already have an existing, working, separate broadband router that you wish to continue using.

The problem with my new assumption is that we need to activate the web configuration tool for the Internet (WAN) socket on the SPA3102. By default this only works for the Ethernet (LAN) socket. If you are not using another existing broadband router, changing this is unsafe, and could give everyone access to your VOIP router, including allowing hackers to make calls on your phone bill and allowing hackers to get access to your computer network.

You may have noticed that the sockets on the SPA3102 are colour-coded and that the indicator lights change colour between red, green and orange. Since like one in twelve white males, I am colour-blind (red-green colour vision deficient), I will not be referring to these colours.

  • Connect your computer to the SPA 3102's Ethernet socket. You can do this either directly, using a crossover cable (easiest way) or indirectly, through your existing network.
  • Change your computer's IP address to 192.168.1.2 with a netmask of 255.255.255.0 . The gateway can be whatever you like, such as 192.168.1.242 (imaginary).
  • Connect your SPA3102 to the mains power and check that some lights, any lights, turn on. Don't ask me what colour.
  • Use a web browser to 192.168.1.1 . You should see the Linksys Phone Adapter Configuration page. If not, your SPA3102 may be using a different IP address and netmask - see the documentation in the box to find out what.
  • Click Admin login - advanced - Router - WAN setup and change Connection Type to Static IP. Change the Static IP, Netmask, Gateway and Primary DNS to the correct values. For instance, on my networks all computers are 192.168.0.something and the broadband router is 192.168.0.254, so I use 192.168.0.252 as my Static IP, 255.255.255.0 as the netmask, 192.168.0.254 as both the gateway and primary DNS.
  • Are both the Internet (WAN) and Ethernet (LAN) on the same subnet? Eg. both have 192.168.0.x or both have 192.168.1.x IP addresses? If so, use the "LAN Setup" page to change the Ethernet address and subnet to something else (eg. 192.168.100.1 netmask 255.255.255.0).
  • On the WAN Setup page, if you know an NTP server (time server), enter it in the Primary NTP Server box. Otherwise use any Stratum 2 UK NTP server from this link. This will mean that the log files and last call details have the correct date and time. Don't worry about this otherwise.
  • Under Remote Management, change:

    Enable WAN Web Server: Yes

  • Click Submit All Changes and wait 5 seconds or so.
  • If you have used a crossover cable, remove it and connect your computer back to the LAN again. Change your IP address back to whatever your LAN normally uses (eg. DHCP). Check that you can still access the Internet.
  • Remove the cable from the SPA3102's Ethernet socket.
  • Plug your SPA3102's Internet socket into your LAN. Yes, you are plugging your LAN into the WAN socket, as I explained in my assumptions above.
  • Browse to the static IP you assigned to the SPA3102. You should see the configuration page again.
  • You should not need to use the Ethernet socket again.

Set the SPA3102 to use British Telecom Standards

No doubt you've noticed on American TV programmes that their phones have a different ring - a single long ring instead of our British two quick rings. Well, the bad news is there are lots of other differences, such as the pitch of the dialling tone, and the SPA3102, despite being shipped with a British mains plug, has factory defaults of the USA. So we'll be spending some time reconfiguring it to sound and act like a British telephone line.

Bear in mind that the dialling tone and ringing tones you'll eventually get when everything is done, will NOT be generated by your local BT telephone exchange like it is now. The SPA3102 will generate its own ring tone, its own dial tone, its own call waiting tone, everything. It'll only connect to your BT line when it needs to, such as an incoming call. So in order for your existing BT telephone handsets to work, and more importantly, your wife not to complain about the phone doing odd stuff, we need to make sure it acts as much like a BT line as possible.

Many, but not all, of the following settings were taken from the excellent document "Sipura UK Regional Settings" by Paul Hayes of ProVu.com . Other settings were taken from the Voxilla.com forums. Thank-you all.

  • Browse to the static IP you assigned to the SPA3102.
  • Click Admin login - Advanced - Voice - Regional and make the following changes:

    Dial tone: 350@-19,440@-22;10(*/0/1+2)
    Ring back: 400@-20,450@-20;*(.4/.2/1+2,.4/2/1+2)
    Busy tone: 400@-20;10(.375/.375/1)
    Reorder tone: 400@-20;10(*/0/1)
    SIT 1 tone: 950@-16,1400@-16,1800@-16;20(.330/0/1,.330/0/2,.330/0/3,0/1/0)
    MWI dial tone: 350@-19,440@-22;10(.75/.75/1+2)
    CWT1 cadence: 30(.1/2)
    CWT2 cadence: 30(.25/.25,.25/.25,.25/5)
    CWT frequency: 400@-10
    Ring 1 cadence: 60(.4/.2,.4/2)
    Ring 2 cadence: 60(1/2)
    Ring 3 cadence: 60(.25/.25,.25/.25,.25/1.75)
    Ring 4 cadence: 60(.4/.8)
    Ring 5 cadence: 60(2/4)
    Time Zone: GMT
    FXS Port Impedance: 370+620||310nF (or 270+750||150nF )
    Caller ID Method: ETSI FSK With PR(UK)
    Daylight Saving Rule: start=3/-1/7/1:0:0;end=10/-1/7/2:0:0;save=1:0:0

    These settings make the dial tone, ring tone and other tones sound like BT.

  • Move to the PSTN page and under PSTN-To-VOIP Gateway Setup, change:

    PSTN VOIP Gateway Enable - No

    This means that the SPA3102 should never answer the phone automatically, allowing the existing household phones and answering machine to answer calls. If you intend to use the SPA3102 to do more advanced things such as voicemail or call redirection, you'll probably want this to be Yes, but that's beyond the scope of this document.

  • Still on the PSTN page, under the FXO Timer Values section, make the following changes:

    PSTN Answer Delay - 60

    This means that the SPA3102 should only answer the phone automatically after 60 seconds, allowing residents or the existing household answering machine a full minute to pick up the phone. If you intend to use the SPA3102 to do more advanced things such as voicemail or call redirection, you'll probably want a shorter value, but that's beyond the scope of this document.

  • Still on the PSTN page, under the PSTN Disconnect Detection section, make the following changes:

    Detect CPC: yes
    Detect Polarity Reversal: no
    Detect PSTN Long Silence: no
    PSTN Long Silence Duration: 30
    PSTN Silence Threshold - High
    Min CPC Duration: 0.09
    Detect Disconnect Tone: yes
    Disconnect Tone - 400@-30,400@-30; 2(3/0/1+2)

    These changes include the BT disconnect tone and also should ensure that calls don't get accidentally dropped due to the SPA3102 mistaking strange noises or quiet volume for a disconnection.

  • Still on the PSTN page, under International Control, make the following changes:

    FXO Port Impedance: 270+750||150nF
    OnHook Speed: 3ms (ETSI)
    Current Limiting Enable: yes
    Ring Validation Time: 256ms
    Ring Indication Delay: 512ms
    Ring Timeout: 640ms

    These settings are more stuff to make your line BT compatible, including a delay to read CallerID on incoming calls.

  • Change to the Line 1 page, and under VoIP Fallback To PSTN check:

    Auto PSTN Fallback: Yes

    This means that if your internet connection fails, it will dial via BT.

  • Still on the Line 1 page, under Dial Plan:

    Dial Plan:(x.<:@gw0>)
    Emergency Number: 999

We are now ready to test the system again. The SPA3102 should now route all incoming and outgoing calls via the BT line even when switched on. If you've unplugged the SPA3102 from your phoneline and handsets, plug it back in.

  • Lift the phone handset. You should hear a dial tone. Try calling a telephone number, such as your mobile or 0800 144 144 (BT chargecard automated service). If this doesn't work, your cabling is wrong.
  • Use a mobile phone to ring your normal home landline number. Your landline phone should ring as normal.
  • Pick up the ringing phone and talk to yourself. Due to echo cancellation on modern BT exchanges, you may have to tap the receiver or do some heavy breathing (ooh-er) in order to hear yourself.

If this doesn't work, try unplugging the power to the SPA3102. If it works when the SPA3102 is off, the problem is with your configuration. If it doesn't work when the SPA3102 is off, the problem is with your cabling.

Once everything works, we are now ready to start routing calls over the internet.

Picking a VOIP SIP Provider

SIP (session initiation protocol) is the open standard for VOIP. This means that lots of companies can all use the same protocol. This is also the protocol that your SPA3102 uses. Skype, at the time of writing (Jan 2008) does not use SIP and you will not be able to use Skype with your SPA3102.

There are lots of SIP VOIP providers to choose from. Most of them will have rates far cheaper than BT. Google for "voip sip calls" and pick one that has the cheapest rates for the destinations or types of call you make most often. For example, my wife makes a lot of 01 and 02 calls, but I occasionally call my sister in Holland.

Remember that BT's national and local landline calls are pretty cheap even on the cheapest tarrif. Many VOIP companies offer bundled, inclusive or free landline minutes for a period if you spend a certain amount, so pick one of those.

Some examples to get you started:

I suggest you put about five or ten pounds onto the account intially. Some providers may take this in Euros or US Dollars. I currently use WebCallDirect, so I will be using this in my configuration examples.

Once you have an account with a VOIP SIP provider, you will need to know the SIP configuration details. These can usually be found on the FAQ or technical support pages. WebCallDirect's SIP configuration details are here.

Some providers will allow you to use your own telephone number, as well as and instead of your username, to log in, so that your Caller ID will be shown to people you call. This is required in order for your name to show up as the caller when you ring your friend's mobile phone, for instance. If you do not do this, your Caller ID will probably be withheld, and people you ring won't know that it is you who is calling.

You may need to do some special kind of registration with your VOIP provider to confirm that you really do own that phone number. For example, WebCallDirect require you to download and run their MS-Windows application and use the account settings options to confirm your phone number with a test call. Once you've done this, you don't need to use the downloaded application ever again - which is good as far as I'm concerned, as I use Linux most of the time.

Many VOIP SIP providers who give specific instructions for the SPA3102 or SPA3000 assume that you want to route all outbound calls via them. This is not the case for us, as we want to route 100, 151, 999 and 0800 calls via BT still. Also we may, at a later date, want to route different calls via more than one VOIP SIP provider (one may be cheaper for UK calls, another cheaper for international calls). Therefore ignore any instructions that tell you to fill in the Proxy and Registration section, as this will route all calls via that provider by default!

  • Go to the SPA3102 configuration page and select Admin login - Advanced - Voice - Line 1.
  • Leave the Proxy and Registration section blank even if your VOIP SIP provider recommends that you fill it in.
  • Put your VOIP SIP provider settings in under Gateway Accounts - Gateway 1. For example, my details are:

    Gateway 1: +441242000000@sip.Webcalldirect.com
    GW1 NAT Mapping Enable: no         (but you may need to enable this; see below)
    GW1 Auth ID: myusername
    GW1 Password: mypassword

    ...where I replace +441242000000 with my home phone number that I have registered with my provider for caller ID, myusername is my account name and mypassword is, surprise, my password.

    If you do not, or cannot, register your home number with your VOIP provider for outbound Caller ID, then replace +441242000000 with your userid (eg. myusername). Yes, this means it gets entered twice - once in the Gateway 1 field, and again in the GW1 Auth ID field.

  • Under Dial Plan, change this to:

    Dial Plan: (x.<:@gw1>)

    Note that you have changed from gw0 (Gateway Zero) to gw1 (Gateway One). Gateway Zero is your BT line, also known as PSTN or POTS. Gateway One is your VOIP SIP provider. Time for another test!

  • From your BT handset, dial your mobile phone using the full international standard. For example, if my UK mobile number is 07711 456789, then I would dial 0044 7711 456789. After a moment, it should ring. Talk to yourself, tap the receiver or do some heavy breathing to confirm it works. Don't worry, we're going to add in some rules so you don't have to dial the full international number, later.
  • Now try dialling the operator on 100. This should fail and thus prove that your calls are going via the Internet because there is no operator on the VOIP system. Don't worry, we're going to add in some rules so that operator and local calls work as normal, later.

If you can't successfully call your mobile (e.g. you get the number unobtainable tone), check the Info tab before you put down the handset. If the Info tab says "Call 1 State: failed" then it is having problems making the outbound VOIP call, usually due to incorrect credentials but sometimes due to router problems. Check your Gateway 1 setting, Auth ID and Password. A common problem is that you may need to enable NAT Mapping, depending on how strict your broadband router's firewall is (some broadband routers are shipped with very strict firewalls by default). So:

GW1 NAT Mapping Enable: yes

Another hint for SIP traffic problems ("Call 1 State: failed") is that some broadband routers try to automatically rewrite SIP traffic, and fail pretty badly. If your router supports SIP ALG (SIP Application Level Gateway) then try turning this off (disable SIP ALG). On some Belkin routers there is a hidden SIP ALG page at: http://your.router.ip.address/siproxdcfg.html

If you still have problems with "Call 1 State: failed" on the info tab during an unsuccessful outbound call, then try putting your SPA3102's IP address in your router's DMZ section (see your router's manual for details). You could even try turning your router's firewall off completely - if you're using NAT then it probably won't matter much from a security perspective, but you should confirm this yourself, or get good advice, especially if you have a server or other machine permanently connected to your network 24/7.

Do not proceed any further until the tests work as expected (ie. you can call your mobile using the international number, but you cannot call the operator).

Configure a Dial Plan

The dial plan determines which outbound calls route over which network - normal BT line or the internet. I'm going to give you a call plan which routes operator, faults, emergency and freephone numbers over the BT line, routes local, national, mobile and international calls over the internet, and bans directory enquiries and premium rate numbers.

  • Go to the SPA3102 configuration page and select Admin login - Advanced - Voice - Line 1.
  • Under Dial Plan, change this to:

    Dial Plan: (100<:@gw0> | 999<:@gw0> | 112<:@gw0> | 151<:@gw0> | 1471<:@gw0> | 0[58]0x.<:@gw0> | 00x.<:@gw1> | <0:0044>[123]x.<:@gw1> | <0:0044>[67]x.<:@gw1> | 084x.<:@gw0> | <087:004487>x.<:@gw1> | <:00441242>[2-8]x.<:@gw1> | 118! | 09!)
    (all on one line)

  • You need to adjust this dial plan for your local numbers. Change the bit at the end, that says 00441242, to match your local home dialling code. I live in the Cheltenham area, so my local code is 01242 and the international version is 00441242. If you live in Birmingham, your local code is 0121 and you'd change it to 0044121 . If you live in London, your local code is 020 and you'd change it to 004420 . Make sure you don't change the chevrons or colon around it.

  • Here's an alternative plan if you just want to route mobile, international numbers and non-geographic over the internet, and continue to have local and national landline numbers routed over BT. Basically the only difference is that we use gw0 instead of gw1 for 01, 02 etc. numbers.

    Dial Plan: (100<:@gw0> | 999<:@gw0> | 112<:@gw0> | 151<:@gw0> | 1471<:@gw0> | 0[58]0x.<:@gw0> | 00x.<:@gw1> | <0:0044>[123]x.<:@gw0> | <0:0044>[67]x.<:@gw1> | 084x.<:@gw0> | <087:004487>x.<:@gw1> | <:00441242>[2-8]x.<:@gw1> | 118! | 09!)
    (all on one line)

    You can read more about customising your own call plan, for instance to route different numbers via different providers, by looking in the "SPA ATA Admin Guide" which can be obtained from the Linksys website, or directly from this Linksys FAQ page. They are similar to, but not the same as, POSIX regular expressions. There's also a lot of discussion on the Voxilla.com forums.

  • Make lots of short, inexpensive test calls and check on your web-based VOIP account that they are going over the internet. If you have BT paperless billing, you can also check on BT.com that you aren't being charged for calls on BT.
  • No, really, check that your calls are being routed correctly before making lots of lengthy international calls! It only takes a typo to change gw1 to gw0 and your calls will run up an expensive BT bill.

If you do not already have Call Waiting with BT, then one way to check call routing is: Call a number that should route over the internet. Leave this call going. Then, at the same time, use your mobile to call your landline number. If it is engaged (busy), then you've done something wrong - it's calling via BT! If it rings, then it is working - and on the normal handsets you will hear a quiet "Call Waiting" beep in the background. Yup, the SPA3102 generates its own Call Waiting system!

And Finally

  • If you previously had an inclusive-calls package with BT, then once you're confident that incoming and outgoing calls are working as expected, don't forget to reduce your BT package. Typically this means "BT Together Option 1".

  • The SPA3102's Call Waiting cannot be fully turned off. The SPA3102 cannot generate a busy tone for incoming calls on the BT line, if you are already on a VOIP call over the Internet, because busy tones are generated at the BT exchange. Instead, when you are on a VOIP call and another call comes in on the BT line, you will hear quiet beeps in the background. You can either ignore them, or you can put down the handset and it will ring with the new incoming call. If you have an R (Recall) button on your handset, you can use this instead to switch betwen the two calls whilst keeping both of them going!

  • Note that both of my call plans still allow 1471 to route over BT, to hear the number of the last caller. If you then press 3 to return the call, this will also route via BT and you will be charged at BT rates instead of VOIP rates. If you already own handsets with Caller ID logging, you don't really need 1471, so you can prevent 1471 from being called by simply removing the 1471:<:@gw0> | bit from the dialling plan.

    To perform a Call Return using VOIP (as an alternative to 1471-3), from the dialtone dial *69 . This will call the last incoming Caller ID.

  • You cannot press 5 to use BT Ringback, for when you get an engaged (busy) tone and want to start a call as soon as it becomes available. Instead, when you get an engaged tone, put the phone down for a couple of seconds, then from the dialtone dial *07 for Automatic Call Back. The SPA3102 will then try to call the number every 30 seconds and will ring when it is available. It will give up after 30 minutes.

  • If your internet connection dies, but the power is still going, calls will route via BT. If your internet connection isn't too reliable, and you're worried about consequently unknowingly running up a large BT bill, on the Line 1 page, under VoIP Fallback To PSTN, change:

    Auto PSTN Fallback: No

  • BT short codes such as *55* for an alarm call will not work, because they clash with existing SPA3102 special codes. I don't know how to get BT short codes to work. If you find out, please email me andrew@aoakley.com .

  • A note about VOIP codecs. Codecs are methods by which the sound data is compressed, and there is a setting available to change this on the SPA 3102 (Audio Configuration - Preferred Codec). I strongly, strongly recommend you leave this at G.711 (basic PCM compression) which will give you very clear call quality and no lag (no echo nor delay). However G.711 requires 64kbit/sec of bandwidth in both directions. If you are on ISDN or have ADSL broadband under 2Mbit/sec (which usually equates to only 384Kbit/sec upload) then you may be tempted to switch to a higher compression codec so you can make calls and use the internet for other purposes at the same time. I strongly recommend you don't do this because the SPA 3102 does not have much processing power and it does not handle complex compression in a timely fashion; you will get garbling, echo or delay. Quite often you can end up in a situation where you can hear the call fine but the person you're calling can't understand a word you're saying, because it takes more processor power to compress data than it does to uncompress it. Leave the codec set at G.711 unless you are absolutely desperate for bandwidth. If you do change the setting, check that people you call can understand you; don't just assume that because you can understand them, it must be alright the other way around; most likely it isn't, and they're too polite to tell you. I'm not going to recommend anything other than G.711 so don't ask what I think is second best; I found that second best basically made me incomprehensible to the person I was calling.

The SPA3102 is capable of much, much more than we've configured here. You can use it to get cheap international calls from your mobile, by configuring it to recognise your mobile caller ID and answer those calls with an international dialling tone. You can use it to interface to an Asterisk software telephone exhange and create your very own voicemail hell. You can use it to store your favourite phone numbers and access them with a shorter sequence. Plus lots, lots more - read the manual and forums for more ideas.

Updates

2008-02-06 Changed Ring Indication Delay to 512ms and Ring Timeout to 640ms, to allow CallerID time to transmit. Corrected duplicate Disconnect Tone.

2008-07-01 Put back missing minus signs in dial tones. Thanks to Theo Markettos.

2009-07-22 Change the Disconnect Tone to 400@-30,400@-30; 2(3/0/1+2)

2010-01-20 Switched dial plan so that 084x. numbers (eg. 0844, 0845) are dialled via gw0 (PSTN). 084x numbers are not usually available internationally.

2010-10-23 Changed FXO Port Impedance from 370+620||310nF to 270+750||150nF . Thanks to Steve Trow, see also the Cisco Small Business Pro Analog Telephone Adapters Administration Guide and this Cisco support forum thread.

2011-02-07 Added router firewall hints for solving "Call 1 State: failed" errors. Absolutely no thanks to Belkin for their hardwired, non-editable firewall and hidden SIP ALG configuration page.

2012-10-25 Corrected the daylight savings time setting to start=3/-1/7/1:0:0;end=10/-1/7/2:0:0;save=1:0:0 - thanks to Garry Martin for the tip.

2014-05-29 Updated to refer to rebranding of Linksys to Cisco, and to note about Local Loop Unbundling. Added section on codecs and why you should stick to G.711 .

2014-06-10 Add coverage of 03 numbers to national dial plan.

Public Domain - Andrew Oakley - 2008-01-08

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