The terminals used in phone sockets are designed to accept a particular size of wire - and it's solid core. They're called insulation displacement connectors (IDC for short). You don't strip any insulation off, you just push the wire down into a slot with a special tool. The slot edges cut through the insulation and nick the wire. This doesn't work too well with stranded wire.
All the alarm boxes and accessories I've seen have had screw terminals. These will work on solid or stranded wire. Stranded is more tolerant of rough handling.