My company is migrating away from our current switch to a hosted provider. In the meantime, in order to make the transition as smooth as possible, we are wanting to do a bulk port of all our subscriber lines through a new SIP trunk established with our new hosted provider to our current softswitch to make the transition as smooth as possible. This would be more ideal so that we can migrate customers at a more leisurely pace if they exist on our current switch as they are, and exist as DID's with our hosted provider sending those digits to us, so that we can provision them slowly as actual subscribers within the ecosystem of our hosted provider during regular business hours. In order to accomplish this, our current softswitch can only do a direct IP SIP trunk (no authentication), but our softswitch provider has to be authenticated. We are considering using an Adtran Total Access 900 series to bridge that gap, as a proxy of sorts. The only question is can the Adtran handle service provider level traffic, say 1000 simultaneous calls? I would appreciate any insight into this. Let me know if you need more information/clarification, as it is a unique scenario.
The TA 900 will not handle the call volume you are asking for. If you are doing SIP to SIP I would recommend using an SBC not a TA 900. You would configure one SIP Trunk as trusted the other as authenticated. The only issue is at that call volume there is no Adtran Device I am aware of that can handle that call volume. The closest I am aware of is the Adtran Netvanta 4430 SBC but it tops out at 300 - 450 depending on if using VQM. I would recommend calling Adtran Pre-Sales Support and see if they can help you out there maybe a carrier level SBC that can handle it I am not aware of. Otherwise you would need to look at doing multiple trunks across multiple boxes with a max call limit of say 250 on each one overflowing to the next in the series and spread it out across 4 devices. One positive to type of setup is that you wont have a single point of failure to worry about if one device where to fail or need maintenance you would only lose 25% of your capacity, or you can run 5 devices and still have 100% capacity in a failure or during any kind of maintenance window.
TA900 series isn't going to come close to that call volume. For a temporary solution, spin up a Linux box with Freeswitch. For something permanent look into a Session Border Controller like Sansay.