Jayeh

Hey all Yesterday best TW ATC were trying to warn aircraft that were going to be very close but weren't getting a response. After they passed another vfr piped up and said they got a hold of them on 126.7 and warned them. There were no ADs that I'm aware of in the vicinity. So what frequency do you guys tune into while xc? I always thought it should be area except in the vicinity of an AD. TIA