We have an application using a SIP trunk, which doesn't need registration. It works fine.
Only there is one problem:
If our system is down for maintenance and restarted, initial incoming calls can be refused for 1 to 4 minutes.
(the SIP provider sends 'alive' checks every 1 to 4 minutes, after answer al works normal)
Because it's an alarm system, we want it to be up and running as soon as possible.
We could force a (useless) outgoing call which will activate the SIP server, but isn't there a more elegant method?
Can we send some start command to the SIP provider?
In this case outgoing call or some other SIP based request (re OPTIONS) would be the only thing that sounds like could wake up the trunk.
There is no specific command per say for that otherwise.