Do I need to backup my contacts etc. if I am switching to a new carrier?
Do I need to backup my contacts etc. if I am switching to a new carrier?
Assuming you're on a GSM carrier (i.e. not Verizon), no. Just unlock your device (if you need to) and swap your SIM card.
If your contacts are on your SIM card then back them up to the device/an email account/something other than the SIM card. You can do so within the Contacts app.