Just a warning for you all, once a false alarm is triggered with the smoke detector, it can't be stopped without the pin being entered. It does NOT matter if their no more smoke. Once the alarm is triggered it CANNOT be stopped with out a pin. Even with the pin, Comcast will still call the police and fire department if they can't get a hold of you to get your password.
So a word of warning if you have the smoke detector with Xfinity Home, if you have guest over and they burn the toast, Comcast will call the police and fire department without someone entering the pin and giving them the correct PW over the phone.
FYI I experienced this personally from Comcast. Luckily I was home though and I was able to enter the PIN to stop the alarm, and I was able to give Comcast my password, but without it they made it clear they would have sent the police and fire department even with the smoke alarm was no longer detecting smoke. SO STUPID.