Shared line/Transfer error

Question

CCM 4.2; Shared line
A receptionist has told me there are times when handling a call on a shared line, and in process of transferring the call that a second call rings to the line and causes an error message "number is not valid" (or something to that affect)and to "please try again later". At that point the receptionist presses "end call" to disconnect from tranfer mode and she is able to reconnect with the call being transferred. The second call was answered and handled, but the first one wasn't able to be transferred due to ??
I'm told by the other receptionists this has also happened to them.
This shared line is an emergency line, and needs to work smoothly. It's set for maximum of 5 calls, with a busy trigger of 2.
Any thoughts on how to prevent the error message from occuring, and tranfer to be allowed to complete when new call is ringing through?
Thank you, Nat

Answer 1

Hey Nat,
Good stuff! Here is some info for "On Hook" transfer;
Onhook Call Transfer
Modifications to the Call Transfer feature add the onhook (hangup) action as a possible last step to complete a call transfer. The Transfer On-hook Enabled service parameter, which enables onhook call transfer, must be set to True for onhook call transfer to succeed. If the service parameter is set to False, the onhook action ends the secondary call to the third party.
In the existing implementation, if user B has an active call on a particular line (from user A) and user B has not reached the maximum number of calls on this line, the Cisco IP Phone provides a Transfer softkey to user B. If user B presses the Transfer softkey (or Transfer button, if available) once, user B receives dial tone and can make a secondary call: user B dials the number of a third party (user C). Cisco CallManager provides a Transfer softkey to user B again. If user B presses the Transfer softkey again (or Transfer button, if available), the transfer operation completes.
With the new onhook call transfer implementation, user B can hang up after dialing user C's number, and the transfer completes. Both the existing and new implementations work in both the case of a blind transfer (user B disconnects before user C answers) and also in the case of a consult transfer (user B waits for user C to answer and announces the call from user A).
The previous implementation remains unchanged: user B can press the Transfer softkey twice to complete the transfer
From this doc;
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_administration_guide_chapter09186a008055cd66.html#wp1088627
When you say "It's after dialing the extension line that they get the error of "not a valid number, please try again later"." Is this a visual message on the display (Probably) or an audible message?
Let me know
Rob