I don't release anything about my subscriber's alarm system to a third party, even when the subscriber authorizes it. I prepare a letter on company letterhead to the subscriber certifying that they have an alarm system, (give the address of the alarm system) which is monitored for fire, burglary, panic, hold-up, system trouble, etc., whatever the system is designed to detect. I add that the Central Station is UL listed, (if that is your case). I give a basic description of the alarm system such as, "there are intrusion sensors on all perimeter openings, interior motion detectors, smoke detector, interior and exterior audible devices," (whatever comprises the system). I sign the letter, scan it into a .pdf, and email it to the subscriber. They can forward the letter to their insurance agent. I've never had anyone object to this method.
Also, when insurance companies call I tell them that I will send a certification to my subscriber and they can forward it on to them. I don't discuss the alarm system over the phone.