Most of the WRC sites use 2 tones. One is used by dispatch in Raleigh to talk to units through the site, and the second tone is used by the units to talk back to dispatch.
For instance, the Concord site on 159.315 ... Raleigh talks on 186.2, and units respond using 151.4.
This method simply cuts down on the amount of voice traffic dispatch has to monitor, as there are about 15-20 sites statewide they have to listen to.
Since units are always listening on the dispatch tone side of the channel for Raleigh, this is also the tone units will generally use to call / talk to another unit in their area. For instance, in the Concord area, units will generally use the 159.315 / 186.2 tone to converse among themselves ... unless they are using a tac channel.
On a couple of the WRC sites, I have heard dispatch use the "mobile" PL tone to converse with officers in the district. And, I have heard comments from dispatchers that lead me to think they can monitor the other side of the repeater pair of tones, if needed.
The easiest way to get the dispatch side tones is simply to monitor the three primary frequencies ... 159.285, 159.315 and 159.345. WRC regularly plays taped I-D / callsign announcements on the repeaters. Depending on your location, you may also hear S.C. Forestry repeaters on 159.315 and 159.345 mHz.
Here's some tone information from my logs ... any corrections are appreciated !
159.285
Winnabow (KJF744) mobiles on 151.4 dispatch on 173.8
Mount Mitchell (KCT234) mobiles on 210.7 dispatch on 186.2
Burlington (KCT238) mobiles on 203.5 dispatch on 186.2
159.315
Asheville mobiles on 103.5 dispatch on 103.5 or 173.8
Canton (KCT232) mobiles on 103.5 dispatch on 173.8
Lumberton (KKW232) mobiles on 136.5 dispatch on 173.8
Lumber Bridge mobiles on 136.5 dispatch on 151.4
Concord (WPBK638) mobiles on 151.4 dispatch on 186.2
Wilkesboro (KKW236) dispatch on 210.7
Sanford (WPKY491) dispatch on 210.7
( The Asheville site will sometimes rebroadcast what seems to be the State of
Alabama Forestry link in Perry County. The S.C. DNR repeater (159.315 / 107.2) at "Russell" (Abbeville County) can sometimes be easily heard in N.C., and it sometimes rebroadcasts the Riverdale, Ga Police dispatches.)
159.345
Boone (WPCQ881) mobiles on 103.5 or 173.8 dispatch on 186.2
Troy (KCT231) mobiles on 151.4 dispatch on 173.8
Henderson (KCT244) dispatch on 173.8
Trenton dispatch on 186.2
Uwharrie dispatch on 186.2
Winston-Salem mobiles on 210.7 dispatch on 203.5
155.460 / 159.090
Forest City (KNAE742) mobiles on 136.5 dispatch on 203.5
( I have only heard Raleigh dispatch on 155.460, but that frequency might be a fixed link, rather than an input. Both the dispatch on WRC officers in the Rutherford County area can be heard on 159.090 mHz. )
My understanding is that both the WRC repeater input frequencies, as well as the repeater output frequencies, can be used for low-power tac channel use ... but there is no PL tone on these tac channels. The repeater inputs are 151.325, 151.385 and 151.460 mHz.
One older resource - "Monitor America" - also suggests the following frequencies may be in use by WRC for unit-to-unit communications ... 151.175, 151.220 and 151.295 mHz.