20 minute splikes and unpredictable vol

Hi. Does anyone have any experience forecasting/staffing for a center that hosts teleconferences? The challenge is two-fold. First, there are extreme spikes 10 minutes before and 10 minutes after the top of each hour (when most conferences are hosted and the agents must “meet and greet” each and every participant). And second, because it is difficult to predict how many particpants will
show up/call in. Throw in the fact that our clients only need to give 24 hours notice to schedule a hosted teleconference…and we have quite a forecating challenge.

Anyone out there have experience with this kind of thing?

thanks!
Jay