The voice frequencies are not automatically displayed from monitoring a Connect Plus control channel.
With DSD+, occassionally a system will transmit its network repeater map as an all call and DSD+ can save this to a file. It will list all the site numbers, LCN #'s, frequencies and color codes.
When I first got started with this stuff back in mid 2014 I used a tapped scanner and DSD+ to verify all frequencies and color codes for a Con+ system. If you're unsure of the frequencies doing a license search may help. I then watched the control channel data to determine talk groups. Control channel data will at least tell you how many repeaters are at the site. So, if the channel activity window lists 20 slots (10 LCN's) you know youre dealing with a 10 repeater, 10 frequency system with 19 talk paths.
After I had determined all system frequencies, color codes, and popular talk groups, I then programmed up a CS700 DMR radio to passively scan the system. Then when a talk group popped up on my CS700, I noted the frequency while watching DSD+ and noted the LCN that talk group appeared on in the DSD+ channel activity window.
Again, this was done in 2014, there maybe better ways today.
Here is a partial snapshot of a DSD+ capture of a local system which transmitted its network map-