The Globe reports [2] Boston School Police, who do not have guns, but who, of course, want them, have a radio system that cannot communicate directly with actual Boston Police - which has its own dedicated school unit. In an emergency today, school guards would have to call their own dispatcher, who would then contact Boston Police.
Links:
[1] http://www.universalhub.com/users/adamg
[2] http://bostonglobe.com/metro/2012/12/26/school-police-raise-concerns-about-equipment-guns-training/JwwVFAdMqsYqBr5VNjZqPO/story.html
[3] http://www.universalhub.com/taxonomy/term/24
[4] http://www.universalhub.com/taxonomy/term/1021
[5] http://www.universalhub.com/taxonomy/term/1399