I have a customer who has a Mitel PBX that I am providing a SIP trunk to (I am the Service Provider). He is requesting that we only send refresh messages and not RE-Invites. I am not sure what he's talking about, however, I am guessing SIP-KEEP-ALIVE maybe? What SIP method is used by the info and options command?
I really don't see a problem with calls here yet. There are some complaints of early disconnects but when we look at SS7 information in our network we usually see a call disconnected from the other end.