If you are ordering a PDA/Smartphone with Sprint Relay Data Only plan, please be aware that this plan has voice service plan restriction. This data only plan is not permitted to have voice service plan added. The Sprint Relay Data Only plan comes with $0.20/min for local voice calls and $0.40/min for long distance voice calls. However, if you wish to have voice plan, you must change the entire service plan completely by start building voice service plan first then add data service on top of voice service plan. Please contact your account executive for more detail.
Incoming calls will be blocked. The incoming call block may be removed by contacting our video customer service (VCS@sprintrelaystore.com), with the exception of the Palm Pre, HTC Hero, HTC EVO 4G, Moment and Pixi. If the incoming call block is removed, you will be billed at $0.20/min for local voice calls or $0.40/min for long distance voice calls. NOTE: 9-1-1 will not be blocked
* Requires a 2 Year Service Agreement
† PAM not available on the HTC Hero, HTC EVO 4G, Samsung Moment, Palm Pre and Palm Pixi.
From Sprint relat store.
Chevy said it included tethering in his post.
http://www.alldeaf.com/1595895-post928.html