Technology saves lives

In the first book, James and Lily don't know Voldemort is coming to kill them, and there's no way anyone can tell them. Since in this post, they have cellphones, Severus texted Lily, and told her that Peter Pettigrew told Voldemort where to go. And he also told her to get out, so Voldemort couldn't kill her. By the way, this was a reply to guests comment. He/she said they didn't get it

They can't have phones because the magic interferes with the electronics therefore they don't work:)

Sorry mobiles didn’t exist in the 1980s.However they might have had a landline. Of course he could just as easily sent an owl or used a fireplace or apparated.

Don't get it