Contacts added from the gnome client don't have the 'ring:' prefix
Issue generated from Tuleap's migration script. Originally submitted by: Alexandre Viau (aviau)
Contacts created from the gnome client don't have the 'ring:' prefix for their phone numbers.
It is best to keep the ring: prefix at all times so that we don't have to guess the protocol based on the number of characters. Other protocols could look like ring.