We have a problem with call transfer.
When a user transfer an internal call to an internal directory number everything works fine. But, when an external call transferred to an internal directory number sometimes it succeeds and sometimes it fails.
We use cucm 12.5 and the cisco 4451 router as session border controller. The structure is simple:
phone---CUCM---SBC---ITSP
What would be the reason? Where does it make sense to search and troubleshoot? I am not an expert. Could you help and guide me about the situation?
Thanks.
