We are going to test connection between two phones.
Our customer has a very complex infrastructure: there are 2 firewalls between CUCM and Asterisk, so I'm not sure there isn't network problems. I've asked to the customer to verify his infrastructure.
By the way, I post you a trace where we have tracked a
SIP/2.0 500 Internal Server Error. It seems that sometimes CUCM answers with this error.
Thanks for your help. Any ideas is appreciated.