Can a Mobile Phone branded 'Vodafone' be used on another network?

[Murphyv310]

I believe it is the phones internal serial number (IEMI) which is hard coded into the hardware that is sometimes locked to a network.
If the phone is reported as stolen to the current airtime provider, then they can mark the IEMI on a central database preventing it from ever being used on any network again.

Note that there is no obligation for a supplier to mark a phone as blacklisted when it's reported stolen, so these checks aren't 100%

There was when I worked for Vodafone!!!!!! Any operator not following the rules got a disciplinary.