Problem: User could not transfer a phone call.
Symptom: Bogus error message about split-domain traffic, with almost no articles on the internet or forums to help. Equally bogus error message was “request target is not assigned to a pool or deployment and is not a server GRUU”
Solution: Disable SIP Refer on the SFB Trunk
Explanation: Not all SBC gateways support SIP Refer, but this is the default option when creating a trunk in Skype for Business.