I think it's quite possible that Maura had a second cell phone--either a prepaid one that she got herself or one that someone else had provided her. Given that the bills for the phone we know about went to Billy's mother, I can't imagine that she'd want Sharon and Billy to be aware of all of the numbers she was calling if she was having relationships with other men, as is claimed on James Renner's blog.
If she did have a second phone, she could have been in communication with someone during her drive to New Hampshire and, indeed, could have arranged to be picked up by someone after her accident. I don't know enough about the area where she had her accident to know whether in 2004 cell coverage was truly nonexistent or was just spotty.
Just a couple of notes:
The phone bill went to BILLY and not to his mother.
Once Maura went missing, billy gave the phone records to his mother to investigate numbers.
There is not one shred of proof that Maura had a second phone. So introducing one into the picture will never prove anything. If we are going to start introducing things, then I get dibbs on the Yeti. I think Maura encountered a yeti the night she went missing.
The Londonderry ping (oh brother, where to start).
A ping is used to track someone, not someone's phone number. Cell phones submit pings when they are turned on (back in 2004) which bounce off of cell towers and reveal the location of the physical phone at the time and place it communicates (vie ping) with a particular cell tower.
What james is bringing up has nothing to do with cell phone pings.
Maura's last known activity vie phone came at 4:37 p.m. Monday where she checked for messages.
That means that shortly after 4:37 p.m., Maura turned off her phone again and it never was turned back on.
It also means that Maura had her phone turned off up until the point she checked for messages at 4:37 p.m.
So her entire trip up north, Maura intentionally had her cell phone turned off with the exception of a few minutes late in the afternoon at which time she checked for phone messages (and at which time her phone sent a ping to a nearby tower).
True story.