I would also check the port holiday override - is for instance port 4 locked in a different mode and calls only experience this dial 0 issue when the other ports are busy.
Experienced with Samsung, Nortel (C/MICS, M1, CPilot/MMail), Panasonic, Zultys, Mitel, now working on Grandstream.
Nurse Call: Ascom TelecareIP, Carehawk HC7000, Luvicom, Stanley, now learning Jeron.
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