Grandstream Networks UCM6100 Manual page 6

previously active call hangs up.
b) If extension 1001 rejected the call or the call went to timeout when 1000 called 1001, 1001 is
considered as available after a new call is completed. This means extension 1001 has to initiate a new
call or answer another incoming call and the new call hangs up. Otherwise, the UCM6100 will not
know whether extension 1001 is available or not.
5. A call will be initiated to extension 1001 to establish call between 1000 and 1001.
UCM6100 Busy Camp-on Guide Page 5 of 10