The Three Second Call Is Not to Leave a Voicemail

I'm still a little bit stuck on why he or the killer would get rid of Maggie's phone but not also Paul's. I do this all the time when my phone falls you know between the couch cushions my husband will call my phone for just a couple seconds so that we can hear it see where it is orientation changes if you're picking it up in order to find it. It honestly really seems much more likely that Alec would want to get rid of those phones than some random killer  but another possibility he shoots them both.