[VoiceOps] VoIP over 3G/4G Data Connection

Jared Geiger jared at compuwizz.net
Fri Jul 25 12:41:55 EDT 2014

I would suggest getting a static IP from the carrier. The Carrier Grade NAT
that US mobile providers use could make stationary phones lose registration
without it. On LTE, you'll be fine with almost any codec that you want. I
typically use ulaw and g722 over 4G LTE with no problems. If you are doing
it over a 3G connection, stick with g729.

TCP isn't mandatory, I use UDP signaling and don't have issues on T-Mobile,
Sprint, or Verizon LTE. I have not tried AT&T LTE and VoIP. I would suggest
talking with the carrier you chose to see what their session timeout value
is. You'll want to set your registration time lower than this to keep the
Internet session up. You may be able to even set the session refresh rate
in the cradlepoint itself. I have not used them though.

Good luck and report back!


On Thu, Jul 24, 2014 at 7:54 PM, Colton Conor <colton.conor at gmail.com>

> What are the recommended settings to successfully implement VoIP over 3G/4G
> data connection? Assume we are talking about using Polycom phones, and the
> 3G/4G data connection comes from a Cradlepoint router that is plugged in
> with AC power and has high gain antennas. The device will be stationary, so
> we will not have to worry about tower handoffs breaking the connection.
> This will be for fixed wireless aiming at a cell tower. I assume packet loss will be a big concern as we have no control or QoS abilities. Plus, the speed fluctuates so much.
> I have read to use G.729 codec, and TCP for signaling to bypass firewalls.
> Besides that, what other settings are recommended?  Changes in MTU? Changes
> in voice payload ms? Is there a better codec to use? Header compression?
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