The reason many are confused because of references to call center is because most Bell County Agencies do not run their own dispatch. I realize that may be contrary to some reports in this thread, but it simply is the way it is.
Any citizen is welcome to stop by Bel County Call center and under many conditions, even get a tour and explanation.
Killeen Police Department does NOT operate their own dispatch, neither does Harker Heights PD, KISD PD, Bell County Constables (all districts) etc. etc. etc!
It does not matter if your in Killeen, Heights, or even Salado, when you dial 911 it rings in Belton at the Bell County Call center and is dispatched from same location.
Inside the Call Center are many terminals. Each terminal is capable of monitoring and transmitting on many different TG's. Here is a recent example, 2 detectives are talking on Killeen Tac 3 (50293 - P25) or 293 (dec) 02-045 (afs) and they will mention something and Call Center will respond "Center Direct" Meaning they are monitoring even though it is the same person who is Dispatcting Killeen on (50289 - P25) or 289 (dec) 02-041 (afs.) Subject then takes off and a pursuit ensues, all involved switch to Pursuit 1 (50417-P25) or 417 (dec) 03-041 (afs) which is an all county, all agency in the county talkgroup run by,,,wait for it,,,,Bell County Call Center. As updates are passed, "Center Direct" is heard by, you guessed it; same young lady mentioned over and over above. By the way, if you get a chance; please go and meet these folks; they are consumate proffessionals that we rely on everyday with our safety.
Right now, with the exception of 2 Temple PD talkgroups. ALL P25 traffic is being retransmitted on the old EDACS system through a bridge, likewise all old EDACS traffic is being retransmitted to P25 through the same bridge. This will continue for quite some time as many agencies do not have the P25 radios yet. So there is no rush to run out and buy a Phase II capable scanner.
I have now mapped every frequency in the old EDACS database to the new P25 databse (inside information, not using a scanner

and with the exception of 5 TG's, the Bell County Conversion plan (which is public by the way, all you have to do is ask for it) is completed by placing a 50 in front of the old (dec) number and badabingbadaboom, you have the complete county P25 plan.
For those who are interrested in the new scanners and how they do on P25 (Bell County); I can now speak for the Uniden BCD 996P2, Uniden BCD 436HP and BCD536HP and finally the Unication G5 Pager. All fall short on Phase II P25 with the exception of the G5 (but it is not a scanner, rather pager that will scan.)
It is frustrating, and I have spent hours messing with P25 Thresholds as well as preamps, 800mhz yagies etc. It seems decoding algorythims are just not there yet in consumer scanners. I can have full strength bars, consistently locked on to control channel, and still miss many transmissions. My series of RTL-SDR's in contrast are almost perfect, just not portable. If anyone is being more successful with the above Uniden boxes, please chime in!
Hope someone finds the above useful and I am more than happy to answer specific questions if I can.