How To Fix T5178 - Extension cannot be deleted because it is being used!

SAP Error Message - Details

• Message type: E = Error

• Message class: T5 - SAPphone: Messages for telephony

• Message number: 178

• Message text: Extension cannot be deleted because it is being used!

What causes this issue?

This telephone number is used in one or more number groups.

System Response

This telephone number can, therefore, not be deleted.

How to fix this error?

If you still want to delete this telephone number, you must firstly
remove it from all number groups.
You can display the telephone numbers used by the different number
groups by choosing Environment -> Deflect call -> Maintain groups ->
Display in the SAPphone system administration.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.