[Mathias]

They're called JELLY CRIMPS! and secrete a moisture repelent gel when crimped on the phone wires to stop ingress of outside elements into the wiring... Funny you should say, but phone wires ARE electrical but work on much LOWER voltages than you'd find in a mains circuit.. Afraid i can't assist you in where to source these terminals, but would strongly advise that a trained tech handle the job!