I have been asked to provide the configuration of a server that can support 120 SIP channels. There will be no switching, no operators. It would run ViciDial to call out and play a standard recording only.
From my own knowledge plus a little googling, I see that there is no standard sizing calculator per se as the hardware depends on other factors. However, I do need to provide something concrete to the client.
As an example, if a few of you who have no PSTN lines, only SIP, can give me a ball park figure as to which processor and how much RAM you have and (roughly) how many simultaneous connection your server is handling, perhaps I can show that to the client.