It could be a problem in the CO. I remember a number of years ago MTS lost part of Gateway (66x prefixes) for about two days. My parents were some of the down customers. Some sort of obscure switch glitch they needed somebody from Nortel to come in and fix.
I also remember we had a problem at work with no dial tone to one of our offices in North Transcona and it was tracked to the remote distribution hut located on Regent Ave by Club Regent. Took the best part of day to change out what ever needed to be done and restore service.