That is completely incorrect. Asterisk can handle 2K calls and more if you have a proper system in place. I have an Asterisk system that does about 1800 calls at once, it’s its only job for alerts.
Also, the suggestion of a SIP Proxy is not a bad suggestion however Asterisk is still going to need to be involved. Most SIP Proxys don’t do media or transcoding so you would still need something at the SBC level for that and you’ll still need Asterisk for everything else like voicemail, etc. That will require things like MWI subscriptions and notifys to have to flow through the proxy to/from the endpoints.
The real trick here is going to be the copper lines. 960 residents with DSL and voice service over their existing copper, what’s the plan to continue to make that work? I get you’re ordering a bunch of 48 port FXS gateways but then what? How do you plan on connecting their house phoneS (yes, plural) as they are probably all wired to the house DMARC which is where the copper would be connect for the DSL/phone service. Even if these are apartments there is more than one phone jack in the residence, correct?
So how do you light up all the phone jacks in a residence and get them back to your 48 port FXS gateways to give them a connection to the PBX? Remember that copper is there for the DSL and is connected to a DSLAM, you just can’t randomly re-purpose that copper and have it at both the DSLAM and the FXS gateways.
Let’s also be perfectly honest here, you’ll never see 2000 concurrent calls on the PBX. It’s just not going to happen. It would require that every phone be in use at the same time. Do you really think you’re going to have 960+ residents and all 17 people in the office on calls at the same time? Not likely. You should be looking at actual call data to determine how many calls actually happen at a single time so you know what you really need. You’re guessing right now.
Right now your biggest concern should be how you’re going to wire 960 residents to the PBX and not break the DSL services that are running over those copper wires. Because right now that copper is terminating from A (the DSLAM) to Z (residence) so it’s going to be interesting how you’re going to make it terminate from A (DSLAM) / B (FXS Gateway) to Z (residence) and still deliver the DSL without degrading it and have it do standard voice over the copper, again without degrading it.
So what is the plan for that?