Asterisk load w/ VOIP phones in small office

In the Asterisk: The Future of Telephony book, there is indication that for less than 3 lines (SOHO system), a computer with 1 GHz CPU and 512 MB RAM is recomended. In my office we are going to have 4 lines possible, with 6 phones. All 6 are going to be VOIP phones, and we may add a PSTN fax machine down the road. Will VOIP phones (I can use G.711, G.726, or G729 with my phones / provider) cut down on the load required of the asterisk server? Do you think a dual PIII 800 with 1 GB of RAM will suffice for my scenario?

Thank you,

One way you can reduce the load on the server is to minimise the amount of codec translation it has to do. I.e., make sure the phones are using the same codec as each other and the same as the codec as used on the external lines (unless, of course, these are POTS lines, in which case they don’t use a codec).

If the example in the book corresponds with the type of setup you want to use, i’d say your system would be pretty close to being up to the job. That’s just a guess though.

I have a similar scenario but with 10 IP stations and a ISDN PBX (one BRI line) going trough Asterisk on a PIII/750Mhz with 256Mb RAM going fine. A blocking rate always exist of course.

Should be enough, but you will only know once you try and see what the load really is. Another way to reduce load is to remove all of the modules you will not be using with Asterisk. The file to have a look at is /etc/asterisk/modules.conf. You may other turn autoload off and load the modules you want, or you may remove modules by using the noload option.

More details here: … dules.conf

And, as recommended more, try to eliminate any transcoding. So, use gsm if you may with your providers and any messages you play, or convert the audio files you use to whichever codec you are using, etc.