I got some strange behavior with one 3CX client within the network I administer. When I try to dial any number in the client in CTI mode, the phone dials the internal number 200 instead. If I hang up very quickly, the IP phone immediately dials the right number. Dialing at the IP phone works as expected. Other clients within the network do work flawlessly. I compared the strange extension with another extension and found no differences. I also tried a fresh installation of the 3CX client and also reset and reconfigured the IP phone. Is there any more checks I can do to nail down the problem?