as others said, this reply is a general answer and may not be applicable to YOUR situation.
around here all county FD are paged out by the SO. BUT the FD is responsible for their own repeaters, bases, and even the paging encoder at the SO. so if coverage is not there, the FD is responsible for purchasing any required upgrades. teh one exception is that some FD members are paged over their trunked radios(page groups are setup to go out 2 tone on conventional and call alert on trunked with a single button push) and the trunked portion it is the responsibility of the system owner(911 in this case) to ensure it has the specified level of coverage. if the problem is with the individual radio, that falls back on the FD or the agency that owns that particular unit, only SYSTEM issues are the responsibility of 911. this is the way it is for multiple counties here that i maintain, but other places everythig falls under 1 roof. your best bet is to let your CHIEF handle the politics involved in getting issues fixed. he/she will know who to talk to for best results. if the chief refuses to do anything, and can't give a good answer as to why they can't, then it is time for several members of the community and the FD to go before the county board with their grievances. but don't run there first, going thru the proper levels of escalation will give better results than just running straight to the top.