German reseller Debitel has launched a spirited bid for iPhone users following T-Mobile’s capitulation into offering an unlocked version of the iPhone. T-Mobile is offering the unlocked iPhone for 999 euros, compared to the locked version for 399 euros, but Debitel is offering a rebate on the difference—600 euros (US$891)—when people bring the iPhone to its network (Debitel resells airtime from T-Mobile, Vodafone, (NYSE: VOD) O2 and E-Plus) reports Reuters. It’s also offering cheaper plans…40 euros a month compared to 49 euros at T-Mobile, which means that for someone paying the minimum it would take 15 months just to get the same level of revenue as the rebate. For that reason it sounds more like a marketing ploy than a solid business decision to me, but it could take a lot of the wind out of T-Mobile’s sails.