To support direct connection of MAP27 peripheral equipment to Zetron’s MPT1327 trunking infrastructure, the Model 427 allows up to four separate 4-wire audio connections. In addition to supporting the MAP27 data interface protocol, the Model 427 includes an extended protocol set that allows it to operate as a multi-port device and to extend the status reporting and control capabilities.
 
The Model 427 interfaces directly to the trunk stack (Zetron’s Model 827, Model 844, and other Model 427s). In a command and control environment, the operators can perform many functions, such as voice calls, disabling users, reassigning channels, dynamic regrouping, deleting users, and management of status messages and data calls.