What if the call was before the um, cough, cough, disappearance? She gets drunk, gets it in her head that JI is cheating. Finds a phone number, maybe in a desk drawer from forever ago, or maybe she found a phone number on the phone a long time ago and tried to dial it by drunken memory. Ends up calling the phone to see who answers. It's a woman, she sound young, and DB decides to take away something of Jeremy's (Lisa) to make him hurt, since now her drunken mind has convinced her that JI is cheating. Cutting off her nose to spite her face, so to speak. There have been a couple other cases where one parent did that just to hurt the other as bad as they could.
Of course, if she were that drunk, then how did she pull off murder, disposal, and cover up well enough to keep herself out of jail for nearly a month now? (See, I even second guess myself.)
BBM
I was just going to go there. At that point you start running into time issues. Wasn't the call made at 2:38am? If she really was as drunk as she says, she couldn't do this by herself.