I know that you can get a gsm phone with a shortwave radio. if you and your buddy has one then that would be like the 10-4 feature. I know my cousin in manila have phones like these. You can use any carrier and still talk to your friends through the shortwave radio if they are close enough. maybe max 5 km radius ?
The "10-4" is much more than just a speakerphone. Cost is the difference. With Bell Solo you don't pay anything for the 10-4 feature until you use it for that day, then it was one dollar all day for that day only and you don't pay for the days you don't use it. And there is no minute charges, and no per message charges. That means you can carry the 10-4 feature without using it and not pay. Say you and some friends all have 10-4 feature. One day you all get together and help organize a kids sporting event. Using the 10-4 feature every friend can listen to and reply to each others chatter all day long. The cost? Only one dollar for each of you! If you try this on conventional cell phones it would be technically impossible, and the total minute charge would be astronomical. Say, 8hours (480minutes * 0.20/min = $96.00 each friend!)
Bell's Solo 10-4 service is similar to the "Nextel" and "Mikephone" service in that you have conventional cellular service and the additional 10-4 service.