Sorry, now i think i understand what you mean. So you cannot complete the transfer process because it gets interrupted by an incoming call?
You could probably try the follwoing CCM service parameter (as you mentioned yourself :) )
Caller ID Display Priority Enabled:
This parameter determines whether caller ID information messages receive the highest priority over most other messages that display on the phone. Higher priority messages will preempt lower priority messages. Valid values specify True (caller ID messages have the highest priority and display for 10 seconds when the phone receives an incoming call) or False (caller ID messages display until the phone receives another message of equal or higher priority; for example, caller ID information and call park display messages have the same priority which means that it is possible for a user to press the Park softkey to park a call and a millisecond later, an incoming call rings and clears the call park display number in favor of the incoming caller ID information. After the the call park display has been erased, it is impossible for the user to determine the number at which their call was parked.)
If you choose True, it is possible that a lower priority message that the phone received while the caller ID information was being displayed will still display, but only if it is not preempted by another incoming caller ID message. For example, if the Call Park Display Timer is set to 20 seconds, in the case previously described where the user has pressed Park and then a millisecond later received an incoming call, the incoming caller ID message will display on the phone for 10 seconds, after which the call park information will display for approximately 9 seconds, assuming no more incoming calls are received.
This is a required field.
Default: True
