This might be an effective solution to the "no cellphones in class" rule. Probably the most important factor is still letting emergency bands through. Does any

This might be an effective solution to the "no cellphones in class" rule. Probably the most important factor is still letting emergency bands through. Does anyone know if 911 calls go through normal cellphone channels, or if that's a dedicated channel that can be 'whitelisted' on a device like this?