Freeze Alert and Cobra PhoneLynx

Hello all. Back from a camping hiatus. We just purchased a class C Sunseeker 3170ds. I want to monitor the temp remotely for the pup in case of a power failure. Spent the last hour pouring over the forums. Everyone says Freeze Alert and Cobra PhoneLynx. We have two cell phones but I'm stuck as to how it all comes together. Anyone know how to set this up? Do I have to tap into the 12v system for the Freeze Alert unit? Any help would be great.
Thanks!