Sprint is upping the ante in terms of services and conditions for people who want to try out its services for a month.

Starting tomorrow, the carrier says it will be offering a new Sprint Free Guarantee to any customer who opens a new line of service. Those who aren’t completely satisfied will get reimbursed for the device purchase and activation fee, get the early termination fee waived, receive a full refund including associated taxes and fees – and they won’t have to pay a restocking fee for new customer exchanges.

According to a comparison Sprint provided in a press release, Sprint’s policy differs from AT&T and Verizon Wireless in that Sprint includes full monthly service plan-related charges refunded, and taxes and fees associated with those charges are waived. According to Sprint, the other two carriers do not offer those kinds of refunds, and a restocking fee “may apply” for customers of AT&T, Verizon Wireless and T-Mobile USA.

Sprint says customers will be responsible for certain charges not associated with the Sprint Free Guarantee, such as premium content, third-party billing and international charges.

So will Sprint CEO Dan Hesse be talking about the new plan in upcoming TV ads? You can bet on that. As part of the guarantee campaign, Hesse will be featured in a TV ad touting the Sprint Free Guarantee that begins airing tomorrow on network and cable outlets. In the ad, Hesse invites customers to join Sprint, “and if you’re not completely happy with Sprint within 30 days, we’ll give you your money back.”