Hi, since nobody else has replied to your question I'll make a suggestion.
You could try BVRP Pocket Phone Tools
(used to be called WinPhone Pocket
) which has an option for sending and recieving faxes via GSM. I've used this software successully under Windows CE 2.11 and HPC 2000 but I don't own a .NET device so cannot say if it would work with your BSquare device or not
You could at least try it - you never know!