Suppose that we know which calls are open, based on the accounting data, so we have all dialog parameters (Call-ID, From, To, C-Seqs, etc...).

How can I terminate a session that is lasting too long?

If I suppose that a session is actually closed (for example because one UA has crashed), how can I be sure that it is really closed (eventually actually closing it)?

I'm thinking to send two BYE messages to both UAs (impersonating the other UA), so to make them close the session (if it is still open).

Is this tecnically possible? Are there any contraindications? Is there a better way to obtain it?

Thanks.