I am using Asterisk to initiate SIP calls that are terminated at a PSTN switch in the neighboring rack at the datacenter (across 100bT ethernet). Our members have registered from their own phone number to receive calls - our authentication process has been OK’d by our paranoid lawyers. We need to plan how much capacity to dedicate to the Asterisk server to handle call volume scaling.
We are planning only to initiate calls, then transfer a single audio file that has been pre-transcoded for sending over the call connection to the PSTN switch, with no IVR or other features/processing. We need to know what will be necessary to support up to 25,000 calls initiated within a 30 second window, and sustained (concurrent calls) for 3-5 minutes. That means how many initiations/calls an Asterisk server can handle, on what hardware. If we need to have multiple Asterisk instances running concurrently, we’d like to have a cluster, so the app that kicks the calls off (a cronjob, and a Postgres/LDAP database of callee phone#s, running on a separate server in the same rack) can handle as simple a network schema as possible.
So, how many Asterisk servers does it take to place and send 25K calls within 30s, running on better HW to minimize the number of boxes?