SAP Message BCOMEC016 - Connection &1 is unknown

Diagnosis
The connection &V1& is unknown to the external software component.
Further information on the external software component:
V3

System Response
The function could not be executed.

Procedure for System Administration
The error can occur in 2 different places:
1. In the connected gateway
2. In the underlying CTI software
In this case the error occurred in (&V4&).
The return code for the underlying CTI software is: &V2&