To switch to TPO, you'll first need to have an unlocked compatible phone. To ensure your device works correctly, you'll need to make sure the APN settings are configured properly. Check out the APN settings for TPO below.
MMS proxy: 22.214.171.124
MMS port: 3128
APN type: "default,supl,mms" on some handsets this will be a “internet + MMS” in a dropdown menu