Enter a valid call code

What causes this issue?

You have tried to execute a call using its call code. Call code &V1&
entered by you is not defined in this configuration of the front
office.

System Response

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

How to fix this error?

Enter a call code that is defined in the current configuration.

Error message extract from SAP system. Copyright SAP SE.