Is this system analog, PRI or SIP for trunks?
IP phones or TDM?
Press the help key followed by the 1st line key, what does it show?
Do you have a data base backup pre-program changes? If so upload it and see if it corrects the issue.
If you didn't do a backup this is a lesson why you should always do one before making program changes.


We get old too soon, smart too late