I have this scenario:
2 SCCP phones (A and C) and a Third-party SIP device (B)
A calls B and B transfers to C, but when I attempt to transfer I receive the error "destination not found" on device (3cxPhone) and error 491: Request Pending, but if I make a simple call between B and C, it works perfectly.
I try this on 3 different CUCM's 7.1.5, 8.6.2 and 10.0.1 and works on 7.1.5 and doesn't work on the others.
What I'm doing wrong?
I found the solution, was missing "Rerouting Calling Search Space" in device configuration.