C Jackson,
ooVoo is great for this purpose. Instead of having someone call into a number, however, with ooVoo you call out to the participant who is not at a computer or does not have ooVoo. Just punch their phone # into ooVoo and it will dial out to them (you need ooVoo phone minutes to do this).
Also, if the user who does not have ooVoo can access a computer w/ broadband, he or she can join the call through their web browser via the web call link in every video conference. Just email them the link and they'll join w/out installing oovoo and they can use video if they have a web cam or just audio if all they have is a headset.
Good luck !!