[stomachmonkey]

The other beni to an unlocked phone is a Dual SIM adaptor.

I carry two phones, one for work and one for personal. But I don't want to carry both.

With an unlocked phone yo can insert a Dual SIM adaptor that will allow one phone to operate on two different numbers from different carriers.

You can't have both numbers active at once yet. (You can buy phones that allow this)

But to get around it you forward one number to the other, if you are active on card 1 and need to return a call on card 2 you software switch the phone.