Server side requirements for a SIP VoIP app

Question

I'm at the beginning of trying to understand the requirements for developing a VoIP app. From what I've learned so far, frameworks that allow for communication using SIP/TCP are the best (I don't intend to implement SIP myself).

However, although SIP can be peer-to-peer, its recommended to use an SIP server service. But I'm finding it difficult to locate information about what SIP services are appropriate for an iOS application / what is required from me in terms of setup of the server so that I can concentrate on client-side development.

Any advice would be much appreciated.

Answer 1

You need to figure out your use-cases to decide. A SIP server is like an HTTP server, it will analyse the request URI, the request headers and whatever hints it can see to execute some resource at the backend. Think if you plan to have a user database and authentication. Do you want presence? Do you want voicemail, call transfers, pbx features? Do you want video, audio, IM? Do you want to support arbitrary endpoints? Encryption, NAT traversal, HA? Only then you can think about actual servers and hosting. Many "minimal" configurations will include at least one SIP/media front-end (for NAT/SBC), a SIP/media server (to act on requests), a database server (to store persistent state) and an HTTP server (for config/admin UIs). While there are products that combine some of these into single server, they are generally at least reasonably isolated modules.