No cell phone while riding, although I do carry one with me but it is turned off until I need to use it. I don't take my dog with me, even on the neighborhood rides that my wife and I do. He's too old and a small dog at that. I wear ear buds when I ride the MUP in the late afternoon. There's hardly anyone on it and I constantly check my mirror to see if there is anyone approaching me from behind. I purchased a set of speakers that are held to your jersey by magnets for when I ride elsewhere. The speakers are small and they are not very loud and aren't made to blast you out of your seat. I have to use full volume on my MP3 player in order to hear the music at a low volume. Also, these speakers are allowed on every sanctioned ride I have been on, including the MS 150. You can hear the normal, surrounding noises quite well with them on.
Here is the link to the company that makes and sell them:
Tuck Away Tunes. It's a local company for me, but I will advise that you get some extra magnets if you decide to order from them as their customer service is the pits.