Da Voismart Knowledge Base.
Call agent login

Asks the agent to login to the system.  Always returns -1.  While
logged in, the agent can receive calls and will hear a 'beep'
when a new call comes in. The agent can dump the call by pressing
the star key.
The option string may contain zero or more of the following characters:
      's' -- silent login - do not announce the login ok segment after agent logged in/off