The "Cary System" talkgroups are used within Cary agencies only.

The Mutual Aid 11 thru 15 C are the Cary TGs on the Tri-Net "Mutual Aid" System. The C indicates they are on the Cary 800Mhz System.
Mutual Aid 6-10 have the D suffix to indicate they are on the Durham 800 MHz system, and 1 thru 5 have the W suffix to indicate they are on the Wake 800 MHz system. They are not relegated to any one discipline (Fire, EMS, or otherwise for their use) but are designed for multi-agency use.