Call and transfer?

I have a video conference unit that will not only establish a video conference but will also automatically dial a phone number at the same time. We like the capability but the mic/speakers on the unit are horrible. I have an expensive conference phone in the same room that we would rather use for audio. The goal is to get the conference phone to dial the number directed from the video conference system. I have a Grandstream HT502 I can attach to the unit and tie back to the Asterisk switch. Any ideas?