The UT-118 will only decode the D-Star digital mode used in Icom amateur radio repeaters or simplex comms. The UT-122 will decode P25 digital voice from conventional or trunked comms., however it will not track trunked systems. It will also allow you to set or ignore NAC codes, but not decode them for you. Only one of these cards can be used at a time in the accessory slot. The UT-122 does an excellent job of decoding P25 comms and the PCR2500 software will display the talkgroups and radio ID's used on a trunked system.