Does the ClearCaptions Mobile app need to be open for me to receive a call?

No. Even if your phone is in sleep mode or is locked, when you receive an incoming call (either from a caller who is dialing your ClearCaptions Voice number or from a caller who is dialing your mobile phone number that you have previously forwarded to your ClearCaptions Voice number), your phone will indicate you have an incoming call. When you respond to the call, you’ll see the ClearCaptions Mobile app icon; tap it to receive the incoming call with captioning.