How To Fix T5103 - No recipient could be determined for call to number &1

SAP Error Message - Details

• Message type: E = Error

• Message class: T5 - SAPphone: Messages for telephony

• Message number: 103

• Message text: No recipient could be determined for call to number &1

What causes this issue?

The telephone number called could not be assigned to a user. There are
a number of possible causes:
The number could not be assigned to a telephony server (it may be that
the available telephony servers are not maintained correctly).
The called number together with the telephony server is not assigned to
a work center. The telephone number and the telephony server must be
assigned correctly before the work center can be determined.
No user could be assigned to the work center (it may be that no-one is
using the device at present).

System Response

Function canceled. The call is not displayed on screen or processed
further.

How to fix this error?

Please check the called telephone number. If the number is correct, you
should check the work center-specific and the client-wide settings.

Error message extract from SAP system. Copyright SAP SE.