All home security "experts" recommend alarm signs. Even the used-to-be burglars who get into home security. They all said that they didn't want to have to bother with the possibility.
Real burglaries aren't like the movies where they disable alarm systems at museums when they steal rare works of art.
This jogged my memory of when my uncles townhouse (off Middlebridge Ln. not far from Glenmont) was burglarized when he was on a work trip. This had to be in the late 90's, though.
They went out back and actually cut the underground phone line before breaking in. He had an alarm that went off, but the message never made it to dispatch. They basically cleaned out his place of all valuables and electronics... he and the cops said it looked like a professional job.
Most alarm systems now have a cellular backup... mine uses AT&T towers. It's not as fast but I feel secure knowing that the alarm signal would get to emergency response.
ALTHOUGH... I had my first major false alarm in my house when I forgot to close the door to my bedroom where my dogs stay when we're out of the house... Indoor motion triggered the alarm and it was going off for an astounding 30 minutes before I noticed on my phone and called back the Ring alarm team. They hadn't dispatched ANYONE yet. Part of me was relieved I wouldn't have cops surrounding my house but another part of me was concerned that response times would be pretty freakin' terrible in the event my alarm goes off in a real emergency. YMMV.