PrefixPlus - add the prefix

PrefixPlus bulk-appends a prefix to phone numbers in Contacts. It preserves the original numbers and adds new labeled entries, for example Call(JP) Home: +81-3-1234-5678 and Call(JP) Mobile: +81-90-1234-5678.

Before applying changes, back up your contacts (e.g., iCloud) to guard against accidents. The extension supports locally stored, iCloud, and Gmail contacts. Note that only those synced contacts will receive prefixes.