broadband wireless(line of sight)

Is there a wat to find out wich providers are on wich towers,i have line of sight to one tower and do not know who is operating it or even if that service is provided from that tower. chers

you could use a tool like netstumbler, a wireless card to check out and a directional antenna to check out what networks are being broadcast off a tower, but it may be easier to talk to your local ISPs and ask them.