Product Spotlight: Linksys SPA3102

July 16, 2008 by Garrett Smith

Many of you may know that Linksys manufacturers a solid, well used and liked Analog Telephone Adapter (ATA) product line. The product line consists of the SPA2102, PAP2T, and SPA3102. For this blog we will focus on the SPA3102 and its “added” capabilities.

On the analog side of things, the SPA3102 can act as a fully functional one- port FXO gateway since it contains an FXO line port. The FXO port can also act as a PSTN failover capability in case the Ethernet network ever fails or drops. It also contains an FXS phone port to connect an analog telephone into. Service providers often times will utilize this device providing their VOIP service to the phone port, and still allow users to use their traditional PSTN or POTS service through the failover capabilities. This is an all around great solution for the home user who would like to leverage VOIP calling through a provider, but still needs the reliability and functionality to their existing, much more expensive, but most reliable PSTN landline network.

On the digital side of things, you will notice that the SPA3102 has two Ethernet ports, a WAN or LAN or Ethernet/Internet ports. This device has built in router capabilities, which can interface both with your public internet service provider as well as your LAN. The device also has the capabilities to act as a DHCP server and “hand out” LAN addresses to your internal LAN equipment. The only downside is you will most likely need a LAN switch to extend, and service network equipment since the SPA3102 only has one LAN port.

Linksys ATA                                               

So what are the added benefits of this $64.99 device you may ask? Home users have been known to take advantage of the FXO port in a most cost-saving effective manner. Let’s describe a quick scenario first and where the gateway aspect of the SPA3102 comes into play. A home user has two locations a great distance apart, let’s say NYC and Alaska (since I’ve always desired to travel there). I am constantly making calls from my Alaskan location to the location in NYC, and to all my buds in the NYC area (local Telco calls) Traditionally, I would pick up my PSTN phone in Alaska and call my friends or location in NYC and incur heavy long distance charges from my telephone provider. In come VOIP and the SPA3102. I simply purchased (2) SPA3102’s and placed them at each location. I then plugged an analog telephone in each of the unit’s phone ports and assigned a VOIP extension, (100 for Alaska and 200 for NYC). Now I can simply pick a phone at any location and call the other for FREE all through VOIP, using NO VOIP provider whatsoever. Next I plugged my telephone line into each of the unit’s FXO ports at both locations. Keep in mind I am still paying for my traditional telephone service at each location. Now, when I pick up my phone in Alaska, I can call into the SPA3102, gain access to my local telephone service in NYC and call as many contacts as I wish in NYC for FREE.

The reason is that when my call comes into the NYC SPA3102, it traverses the VOIP network from Alaska to NYC, (where my Telco whacks me with long distance fees), and when I gain access to the local Telco in NYC, my call from Alaska “looks” local to the NYC Telco provider and I incur no long distance fees whatsoever. This whole process of “extending local dial-tone” has been a blessing in disguise to home users who frequently pay high long distance fees from their telephone. If it makes you feel better, you’re tricking your phone company, and even better, this scenario will work at virtually any location where you have broadband internet access, so you can pick up and move virtually anywhere in the world.


  • Neat. I’ve always used these ATAs by linking them to an Asterisk switch. I did not know that one could talk directly to another. And details on setup info? Thanks, Stuckey

  • I have one of the older spa3000 boxes and have had quality issues using both ports at once. Have there been improvements in echo handling and general voice quality with this new model?

  • Mike Edwards

    Hi Chris,
    Great article on the 3102. I have been using this device for the last two years now in a scenario like you describe above. It has been a great solution for me. However, I do have a question for you. A 911 dialplan, do you have any experience with this? I would like to setup the 3102 so that if the extension goes off-hook and dials 911 it will route the call out the FXO port. Currently when I test this my call still goes to the remote side (you can see the problem here). For the time being I have had to put a note on each extension that 911 does not work from this phone, but I would like to make it work correctly. Any suggestions?


  • Larry

    Very nice! How do these two remotely placed units track each other over DHCP ISP accounts?

    I would imagine these can be placed anywhere worldwide and could then port local PSTN telco lines into my Asterisk PBX server. :o)

  • PhoneEd

    For Mike, this dial plan in my 3102 uses the FXO for x11 calls, anything dialled as 10 digits (local calls) as well as calls to tollfree numbers.


  • PhoneEd

    Well, that didn’t work so well. The blogsite ate the special stuff that tells the dial plan to use the FXO.

    Let me see if I can use HTML definitions to insert those special characters.


  • Mike Edwards

    This is exactly what I needed, thank you for the help!

  • Larry,

    The two devices talk to each other via IP addresses. It is strongly suggested when using these devices in a point to point (spa-3102 to spa-3102 pure VOIP) and back to back (spa-3102 over VOIP to spa-3102 then out PSTN) that you set each unit’s IP address statically. Using them within a VPN or LAN environment cuts down on NAT issues and one way audio issues, and even placing both units on “public” static IP addresses provided by your ISP is suggested. There is often a charge associated with this however. And you can also use this device as an external FXO gateway to your Asterisk server as well.

  • Stuckey,

    I am getting instructions created as we speak and will update everyone on how to obtain them when available. I will like to note that when these instructions become available, they were tested and proved working with a PSTN landline (NOT using an analog PBX connected to station line) as this is another common application for this device. Like I said I will update everyone when this becomes available.


    Chris Heinrich

  • Jared,

    I have never experienced any echo problems with the spa-3102 in that type of scenerio or for that matter cross talk. The only real difference between the spa-3000 and spa-3102 is that the 3102 can act as a router where the spa-3000 is a LAN device. The firmware on these units are more up-to-date than the spa-3000 so that may have something to do it. Hope that helps.

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