Set the phone to delayed ring instead of immediate ring. The calls are ringing simultaneously at the phone and the 007MLM. With delayed ring (instead of no ring) you will be alerted if all ports of the 007MLM are busy and can't take another incoming call.
Dialing 0 rings the phone connected to the first logical station ID, so perhaps that is not your "operator" extension, and there is NO phone connected to logical id 01?