I've received a new sim from a new supplier for my mobile network, I have obtained from my old supplier a PAC number to retain my number, at what point should I insert my new sim?
If you supplied the PAC code to your new supplier before activation, then on activation day you can swap the SIM’s when the old SIM stops working.
If you are moving to BT Mobile then you can insert your BT SIM and use either the temporary number that came the SIM until the number ports over, or activate the BT SIM via your BT account. If you are porting into BT you can also input your PAC in your account too.
If you are moving away from BT then you can swap SIM’s when the old providers stops working.