I think there may be a little confusion here. The LTR system the OP asked about was for communications related to the various rental car agencies and related shuttles to transport customers to/from the parking lot to the agencies - which used the 900 SMR system.
The encrypted UHF Cap+ system used by GOAA mentioned above is used exclusively by GOAA for various airport operations such as terminal ops (landslide and airside), airfield ops, maintenance, custodial, access control, comm center, baggage control, tram, parking, and security (not to be confused with the OPD PD airport division).
Some of these functions previously were on the old Orlando P-25 system (Greater Orlando Public Safety Cooperative - system 25A) and were later converted to the Cap+ system. GOAA Emergency Services (ARFF and EMS are still on the County P-25 system as well as OPD airport division (later of course ENC).
So I'm not sure where the users of the 900 MHz LTR system went, but like it was mentioned they may have gone to local SMR systems like Suntalk as djlolli mentioned. I'm too far from the Airport to confirm any activity.
The encrypted UHF Cap+ system used by GOAA mentioned above is used exclusively by GOAA for various airport operations such as terminal ops (landslide and airside), airfield ops, maintenance, custodial, access control, comm center, baggage control, tram, parking, and security (not to be confused with the OPD PD airport division).
Some of these functions previously were on the old Orlando P-25 system (Greater Orlando Public Safety Cooperative - system 25A) and were later converted to the Cap+ system. GOAA Emergency Services (ARFF and EMS are still on the County P-25 system as well as OPD airport division (later of course ENC).
So I'm not sure where the users of the 900 MHz LTR system went, but like it was mentioned they may have gone to local SMR systems like Suntalk as djlolli mentioned. I'm too far from the Airport to confirm any activity.