6D Phone - Ringing Instead of Dial Tone When Intercom Button is Pressed

[EEYooper]

Recently had to replace and reconfigure settings (no backup) on the ACS R6.0 module. One extension using a 6D phone has a problem. When either INTERCOM button is pressed, instead of the system dial tone, there is a phone ringing sound. It never goes to a voicemail box and no other extensions appear to be blinking.

It is my understanding that the Intercom buttons are not programmable. So I am puzzled. Which settings must be changed so that the system dial tone is heard when the Intercom button is pressed?

 

[TouchToneTommy]

Try #505-7-xx-2 for the phone in question

 

[EEYooper]

I went through all 8 hunt groups for this extension. It was assigned to hunt group 3 for some reason. Even after unassigning the extension from this group, the problem still persisted. After putting another hour into this, I found that this extension was mistakenly set as a hotline to another extension that is no longer used. The #603 REMOVE for this extension took care of the problem. Thanks for the suggestion.