Recently Gmail started recognizing phone numbers in email contents and converting them into clickable links. Once clicked, it shows ‘phone’ similar how it shows gtalk chat sessions:
I haven’t tried the calling feature itself yet, but I think that regular expressions should not pick up IP addresses and convert them to phone numbers. I’m not sure if it’s solvable programmatically, but who writes their phone number as 4 groups of digits separated by points anyways?