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Is there any option for screen sharing through portable devices?

I remember being impressed when I used it the one time that I tried to sign up for it but ultimately gave up. Is it possible to use it without a credit card?

I'd love to start selling something similar to coaching sessions with UberConference. I believe I will want to direct new people through adds to a scheduled conf. call, where I want to end by giving them a very visible and clickable link to an opt-in page for buying a product, give their contact information, etc. It would be wonderful to execute such a business adventure with ease and flow, preferably through a guided UberConf. video, and a written down step-by-step. (In the future, UberConference could be a live webinar service for me? :D)