Consumer Cellular is an MVNO that either uses AT&T or T-Mobile as its carrier. Most users are on AT&T's network. According to this prepaid phone news article, if your SIM ID (ICCID) "starts with 890126 it's for T-Mobile, AT&T SIM IDs start with 890141."iOS users: Go to Settings > General > About and look for the ICCID number.Android users: Use the SIM Device Info app that displays the SIM ID as "SIM Serial Number."So when you choose which carrier to use in an account or member profile, select AT&T instead of Consumer Cellular if you are on AT&T.If you are on T-Mobile, we will soon issue an update to work with that.