I've read some ISPs give it within 15 minutes by email. That's pretty fast!
A MAC is a unique code, identifying a particular line. It comes in two formats. You do not need to worry about which format is used:
- a code consisting of four letters that identify the underlying service (BBIP, FTIP or BBDS) followed by between seven and nine numbers, a slash, and five alphanumeric characters (e.g. BBIP1234567/1F6HT); and
- a code consisting of four letters (LLUS), followed by six digits followed by four further digits showing the expiry date (i.e. LLUS123456ddmm).
A MAC code is only valid for 30 days.
MAC stands for Migration Authority Code