[asterisk-users] Help with concurrent VoIP calls

[John Timms]

Hi. I'm having trouble figuring out why I'm not able to make many
concurrent VoIP calls on my system. I'm not aiming for a huge number,
because I have purposely bought a low powered system, but I would
think that I could get more. Here are the details:

I have a small-form-factor Asterisk server with an Intel Atom 230 CPU
(1.6 GHz, 533 MHz FSB) and 512 MB DDR2 533. It is running Ubuntu
Server 9.04 with the default Debian package manager installation of
Asterisk. (version 1.4)

Here is what is going on: I'm making outgoing calls (with .call files)
via SIP (using Vitelity's service, if anyone wants to know) with about
55.0 ms latency between my Bellsouth DSL connection & their servers.
I'm using GSM-format prompts with GSM encoding (disallow=all,
allow=gsm in sip.conf) and I'm able to make about 7 concurrent calls.
I have a very fast internet connection, so there is still plenty of
bandwidth, and the "top" command shows that Asterisk is only at about
5% CPU and 10% RAM. Even with only 7 calls, a landline phone will
"skip" occcasionally, but cell phones have perfect quality.

I don't think that 7 calls is very many, I'll be happy if I can get 10
good-sounding calls. Can anyone give suggestions? (If this has been
hashed out elsewhere, I'm happy with a link to more information!)

Thanks.