Nope, it's part of the core plan. On your phone check the following settings:
1) Turn on Data Roaming
2) Set Preferred Network to 4G/LTE vs 5G
3) Set Network Selection to Automatic. If this doesn't work, manually connect to T-Mobile or AT&T.
For phone calls to work you need to ensure you have a VoLTE capable phone per PM's list:
https://www.publicmobile.ca/en/on/get-help/articles/volte
