»www.sasktel.com/attachments/vist ··· nual.pdf
Here is a copy of a manual for a Vista 390 phone, might be Options instead of menu.
I have seen these phones 'customized' slightly in the past.
But I believe you have to remove the area code, not add one.
Adding an area code, causes it not to be recorded/displayed on the callers list.--
Yes, I am not employed and looking for IT work. Have passport, will travel.