Line 1 button not working 1

[zete]

In a Partner ACS there is only 1 phone that line 1 cannot be accessed. I tried a known good phone and got the same result.... All the other phones in this office can access line 1, receive calls from line 1, and trasnfer calls that come in on line 1????
Any ideas?? I have a battery alarm and I do not want to restart and reprogram a system that may not come back up??

 

[TouchToneTommy]

Easiest way will be to copy from a working extension - #399-(working extension number)-(non-working extension number)

Otherwise, if you want to find the actual problem, look at Line Access Restriction, #302-(extension number)-(line number)-(1=No Restriction/2=Out Only/3=In Only/4=No Access)

Back up the programming with #124, and replace those AAA batteries (with the power ON)