Alarm sounded, police notified, and criminals gone. Simple. Here is something you may not know: your alarm system does _not_ connect to the police.
Your alarm system subscribes and connects to a Central Alarm Monitoring Station (CAMS). The CAMS then relay your information for police response.
There are two wired ways to connect to CAMS: dedicated data line (DDL) and regular phone line.
DDL is a must have for security function because:
1) Unlike phone line being a best effort service, DDL is a guaranteed service.
2) Unlike phone line being a non-monitored service, DDL is a monitored one. If a line is at fault or cut, CAMS would be notified immediately.
With so many alarm systems and CAMS services available, it is important for your consultant to find out if the two are technically compatible.