I just added a forth CO to the system all if fine everything works except one extension the line key is programed as an extension. what can I do.
Line keys are programmed in Memory Block 4-12: select the appropriate station port to be programmed, then key number, press LineKey 2 to assign CO trunk, then use the dial pad to input trunk 4.
Make sure of the port number for that phone by pressing feat+4 before changing any programming.
I did that the line works fine the 4th button is co 4 on all phones except one phone " not the programing phone"