The probability would be more of a carrier/exchange issue that does not route correctly. And this has been a common occurance reported accross the board here where people have reported dialing issues
You just need to keep a log, and report it to Ooma.
For example, attempting to dial 695-72xx (using my cordless phone's phonebook or dialing manually), I'd get connected to 699-57xx (an extra "9" dialed and throws the entire number off). I have a bunch of cases of this in the call logs where it's obvious what number we were trying to dial and several failures in between.
This never happened when we got the system (admittedly only in January). Seems to be relatively recent.
Of course, I tried to power cycle the system this morning hoping to resolve it and now I've got nothing but a blinking red box. Serves me right, I guess, for trying to fix it. Should have just kept pretending the wife was crazy.