Code review comment for lp:~renatofilho/address-book-app/input-hint

In general we normalize the phone numbers before making calls. So the non diable characters wouldn't be a problem.
It is commom to use () for area codes. IMO we should allow users to enter those chars
Also, comma should be considered as diable, it means to stop a second before dialing the next numbers, used mostly to call extensions IIRC.