SAP Message BCOMEC019 - The maximum permitted number of users logged on has been reached

Diagnosis
The maximum permitted number of users that can register on the externalsoftware component has been exceeded.
Further information on the external software component:
V3
The server concerned is &V1&.

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&