Comments on: Setting Up PBX in a Flash, Part 4: Configuring a Linksys SPA3102

By: John Murray

John Murray — Thu, 20 Jan 2011 15:16:20 +0000

Incredible. I have been working on this for hours. However, with your post, I was able to spend 10 minutes configuring parameters and everything worked the first time!

In my configuration, I am not using the ethernet port on the 3102. Rather, the WAN port is connected to my internal network. PIAF and my polycom 331 are both connected to the internal network. I have the bridging configured as you have and have used a static IP for the 3102.

Thank you! I am now making outbound calls over the PSTN when they are local and outbound calls over VoIP when they are long distance.

thank you!

By: Mark Berry

Mark Berry — Wed, 21 Jan 2009 20:33:10 +0000

Thanks Fred. It does seem incredibly complex to configure an ATA, especially compared to just plugging in an analog phone and having it work.

Although my phones have been ringing okay, I will try Ring Frequency of 20. From some additional reading (http://www.sundance-communications.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=24;t=000576), I have the impression that CO line voltages are not always up to spec (90), so I’ll set Ring Voltage back to its Linksys default (85).

A bigger concern is general voice quality, which has intermittently been pretty poor, not to mention that outbound faxing fails most of the time. I’m anxious to see if setting the RTP Packet Size to 0.020 helps with these issues. Here’s an additional article on RTP Packet Size: http://michigantelephone.wordpress.com/2007/11/16/linksys-and-sipura-adapter-users-check-your-rtp-packet-size-and-newtork-jitter-level/.

By: Fred

Fred — Fri, 16 Jan 2009 01:43:25 +0000

There are many guides for configuring the SPA-3102 out there and most of them manage to get something wrong. One thing I noticed here is that the Ring Frequency is wrong for the U.S.A. and Canada – while it probably won’t matter if you only use very modern phones, if you try to use an old Western Electric or similar phone it probably won’t ring until you change the ring frequency to 20. Also, the correct ring voltage is 90 volts – slightly lower voltages may work, but they aren’t Bellcore standard.

Another thing to note – this is from the page “How to setup a Linksys SPA-3102 or Sipura SPA-3000 with FreePBX” on the freepbx.org site (which is the most comprehensive guide I’ve seen on the subject) – http://www.freepbx.org/support/documentation/howtos/howto-linksys-spa-3102-sipura-spa-3000-freepbx

Check the RTP Packet Size!!!
VERY IMPORTANT: Before you do anything else, go to the SIP tab. Look under RTP Parameters and check the RTP Packet Size. Linksys has set this to 0.030 by default, which is not correct for use on ulaw (G711u codec) connections. Change it to 0.020 instead (or 0.02 on older Sipura devices). If you don’t do this, you may experience strange problems with “choppiness” or random clicks on some calls but not others, and you may also experience problems when playing Asterisk sound files. By the way, this applies to all Linksys/Sipura adapters, not just the SPA-3000/3102.

I can personally attest to the above, there was a very annoying clicking in the receiver until I changed this.

By: Charles Allen

Charles Allen — Mon, 01 Dec 2008 09:24:44 +0000

This is some good information. By contrast here’s a pretty amusing video that shows how to set up extentions on a hosted pbx: http://www.youtube.com/watch?v=8NwcF2pvalk

Best,
Charles