Highly, highly, highly recommend you enable 911 calls by default on all plans -- let parents disable it if they want. Cell phones do this, even without a SIM card. Don't gate safety for $9.99/mo.
Edit: "The FCC requires that providers of interconnected VoIP telephone services using the Public Switched Telephone Network (PSTN) meet Enhanced 911 (E911) obligations." https://www.fcc.gov/consumers/guides/voip-and-911-service
Also "911 Services: Providers of "interconnected" VoIP services – which allow users generally to make calls to and receive calls from the regular telephone network – do have 911 service obligations" https://www.fcc.gov/consumers/guides/voice-over-internet-pro...
Edit: "The FCC requires that providers of interconnected VoIP telephone services using the Public Switched Telephone Network (PSTN) meet Enhanced 911 (E911) obligations." https://www.fcc.gov/consumers/guides/voip-and-911-service
Also "911 Services: Providers of "interconnected" VoIP services – which allow users generally to make calls to and receive calls from the regular telephone network – do have 911 service obligations" https://www.fcc.gov/consumers/guides/voice-over-internet-pro...