Same talkgroups on two different P25 systems?

[som]

Okay, I noticed something a little strange today while finding and listening to talkgroups on the City of New Orleans Government system. Two of the talkgroups I've found share identical numbers with talkgroups on the LWIN system - and they both sound like the same sort of traffic as well. 29562 on the CNOG system is definitely a NOFD talkgroup, and it also happens to be NOFD Dispatch on LWIN. 29700 sounds like EMS dispatch on CNOG, and it's EMS dispatch on LWIN.

Anyone have an explanation for this? Can two totally different systems share the same talkgroups?

 

[wa8pyr]

Okay, I noticed something a little strange today while finding and listening to talkgroups on the City of New Orleans Government system. Two of the talkgroups I've found share identical numbers with talkgroups on the LWIN system - and they both sound like the same sort of traffic as well. 29562 on the CNOG system is definitely a NOFD talkgroup, and it also happens to be NOFD Dispatch on LWIN. 29700 sounds like EMS dispatch on CNOG, and it's EMS dispatch on LWIN.

Anyone have an explanation for this? Can two totally different systems share the same talkgroups?

Certainly. They probably coordinated it that way for simplicity.

It's also possible that the two systems are using an ISSI (Inter-RF Subsystem Interface) box to connect the two systems together, in which case it's like a glorified "patch" that allows a radio to roam from one system to the other.

There's also a CSSI (Console Subsystem Interface) standard that allows dispatch consoles to connect to multiple systems.

 

[som]

I had no idea, but it makes sense. Thanks for the info!