Codec and Bandwidth Questions

[larrybob]

 I would like to use an obi for travel, and recently have run into problems when I tried using the obi with GV  at various hotels over WiFi. Often the incoming sound had good quality, but the outgoing sound using GV was choppy and garbled.
I am guessing that the outgoing band with was not sufficient .
I do not have knowledge of how the codecs and the voip provider are connected. (for example; can you choose different codecs to work with GV, or if you want to use a lower Bandwidth codec, do you find a different provider.
Can you give me any advice, on possible solutions that would let me use the obi device in places where often, the out going bandwidth will be slow.
Thanks so much!!
Larry

[hwittenb]

You can't choose the codec with GoogleVoice. I understand they only use G711u.

Voip providers will support different codecs.  The standard codec used with the sip protocol is generally G711 which has probably the best sound and requires about an 88 Kbps bandwidth each way.  The G729 codec requires only 31.2Kbps each way (send and receive, i.e. 2x the quoted figure).
http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080094ae2.shtml

You can setup your ata to only allow a certain codec but you have to make sure your voip provider supports that codec to the calling locations that you usually call.  If you do this you should run some test calls ahead of time to make sure your call is going to go thru when you really want to call.

Voip providers will usually have a FAQ about what codecs they support.  CallCentric is one good provider that does support G729.
http://www.callcentric.com/faq/8/100