Work order, digitally signed, paperless

Now, my technicians bring a 3-copy work order notebook. When a ticket has been resolved, they manually fill the work order form, description of work and materials, and has it signed by customer, manually, by pen. One copy rest at customer site. Then, back in office, second copy goes attached with invoice and third in archive. Now, technicians should reprint the work order in Resolution field of Tickets to have it in digital form. That is the point where humans nature show its face.

As we use a mobile access to SCP, I would like to have my technicians fullfil a virtual work order on site and have customers sign it on their smartphones or tablets touch screen, paperless. In office, clerk can print out that work order and attach it to invoice. Everything has been already in database. Voila!

Any idea?