[Asterisk-Users] g.711 to GSM gateway

[Steven Critchfield]

On Mon, 2003-03-10 at 06:04, Cerrajetto wrote:
> Hello:
> 
> I would like to implement a VoIP telephony system; client's
> software/hardware only supports SIP with the g.711 codec.
> 
> It's very huge in wan communications (about 110 Kbps) !!!
> 
> I'm looking for systems that could reduce this bandwidth, at this time I
> can't change the client side.
> 
> Can Asterisk act as a gateway to convert g.711 to GSM, and then reduce the
> wan traffic?. The idea is on-the-fly conversion:
> 
> client 1 -> Asterisk GW 1 -> wan -> Asterisk GW 2 -> client 2
> 
> client 1 calls client 2 and sends g.711
> Asterisk GW 1 converts on-the-fly g.711 to GSM
> Asterisk GW 2 converts on-the-fly GSM to g.711
> client 2 receives g.711 from client 1
> (and vice-versa)
> 
> Is it possible to do it with Asterisk?

Not only is it possible, but you can convert from SIP to IAX and gain
the ability to go behind a NAT firewall with ease.
Client1 G.711 SIP
Asterisk SIP receipt
Asterisk IAX GSM transmit
WAN
Asterisk IAX GSM receipt
Asterisk SIP g.711 transmit
Client 2

Similar to what I used at home with a ATA186, ata to asterisk via G711
SIP, IAX from my asterisk machine to the office using GSM, then offload
to PSTN.
-- 
Steven Critchfield  <critch at basesys.com>