The keypad is cellular connected, as well as using your local Wi-Fi network for cameras, locks, etc, and low power BlueTooth (Z-Wave) for the security telltales (doors, smoke detectors, and motion detectors).
I doubt it'll be GSM. Telus doesn't have a GSM network and the only provider in Canada that has one is shutting it down nation wide, next year.
I believe the security systems use the telus mobility network to communicate to the monitoring station. I think this because under service eligibility it say you must live in the HSPA coverage area.