Gordon Henderson wrote: > On Tue, 19 Feb 2008, sean darcy wrote: > >> using asterisk(A) over iax to another asterisk server(B) which connects >> to pstn over pri. >> >> Doesn't B have translate to ulaw whatever goes out to the pstn, > > Depends on the country, but ulaw or alaw...
ulaw > >> so >> therefore shouldn't A choose ulaw as the iax codec to B? That way >> there's no loss translating from {gsm, ildc, etc} to ulaw on the B server. > > It depends on how the call comes into A and how "bothered" A is about > doing the transcoding, or letting B do it for them. > the call comes into A over an analog port on a TDM400P. I assume it's ulaw. > If the calls come into A via GSM, then you might as well send them out > again in GSM as the call quality won't improve, but if they come into A as > G711 (ulaw or ulaw) then keep them as G711 if you don't want to lose > quality, else compress them to GSM if you don't have the bandwidth > avalable. > >> My partner thinks I'm nuts, and that gsm is much more "efficient" as the >> iax codec. > > GSM is more compressed than ulaw or alaw, so will use less bandwidth, but > in doing so, it will sound worse. (mobile phone quality rather than > landline quality) > >> BTW, we have 512kbs over the iax connection. > > G711 needs about 80Kb/sec each way to work. (It's 64Kb/sec plus IP > overhead). GSM needs about 32Kb/sec (13Kb/sec plus IP overhead). > So with DSL 512kbs up and 3mbs down, plenty of room for G711. Of course, I could figure out how to configure QOS in iptables for asterisk, it'd be a lot better. > IAX is more efficient than SIP in packing multiple calls into the one data > stream. > >> Whom do you support? > > My customers, and what they ask for... > Great. Thanks for the help. > Gordon > sean _______________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users