APCO Project-25 wireless data link is a Narrow Band wireless link. This causes communicataion link to have very limited bandwidth which is between from 4 kbps up to 7.2 kbps. In such case we are in search of every, opportunity to improve and well-utilize this low-bandwidth channel for data communications. In this paper we study two data communication modes of APCO Project-25 Data Communication structure and offer to change these modes dynamically to improve efficiency. APCO Project-25 Data Communication Modes are; 1. Confirmed Communication and 2. Unconfirmed Communication. For Confirmed Communication Mode, all packets are protected by 314 Trellis Code and for each packet received, other party sends confirmation package. For Uncofirmed Communication Mode, 1/2 Trellis Code is used for protection and there is no acknowledgement. In both modes, each packet has its CRC information. Based CRC success/fail statistics, system will decide to switch to other in order to increase bandwidth or provide robustness of communication.