GETREMOTEPARTYUSERID
GETREMOTEPARTYUSERID(userid AS INTEGER, langid AS INTEGER) AS BOOLEAN
Returns in <userid> the identifier of the remote party user; the user language identifier is returned in <langid>.
The function returns TRUE if there exists an ALERT user with the remote party phone number. If the user exists, <userid> contains the user identifier; else the returned value is FALSE and <userid> is set to 0.