Cell link would be no problem for quality I think Barythin, I'm thinking of Aircard type adapters for contemporary laptops that allow wifi access through cell network. Also, we use a hardware codec at work called Tieline to do remote broadcasts, and they'll work over POTS, IP, or over cell networks if you get the GSM addon card for them (at $1k or so I think, lol). The quality and bandwidth is definitely there.
Now, the whole modding the modem to work over cell I'm not sure how to go about that.....