Phone rings during app use, even when phone is on silent

I really like this app and I use it often for my 9-month old. However, if I have an incoming call on my phone, my ringtone plays at high volume through my Bluetooth speaker waking up my baby. I try turning down my ringer volume in addition to having my ringer completely turned off. It doesnt happen when I get a text, only an incoming call. I dont use an iPad or tablet, only have a phone, so I have to pray no one calls during nap time or keep the phone with me to silence it as fast as I can hear it ringing from her room. You can see how impractical that is. Other than that one complaint, I really do like this app. I hope this is an issue that can be fixed.

Kpetru about Sleep Genius Baby