To add to what Fineshot said, recent studies have shown that "digital" is not recommended for fireground communications. I believe it was FDNY and a few other big city depts that recently did a study since they found them to be unreliable.
digital comms are being blamed for the death of a Virgina firefighter last year i believe. many depts hearing this im sure got scared away by it. but there are systems near by me that have digital PD and EMS, while fire remains separate,