If you were hoping to unlock your iPhone using one of the two solutions that came onto the scene earlier this month, you're out of luck. Both Cut Your Sim and GSM Phone Source no longer offer their services.

The two providers promised those with an iPhone 4 a way to get a "permanent" unlock to use their device on the network of their choosing, with no need to jailbreak or worry about future software updates affecting the fix. Such functionality is especially appealing to travelers who seek to avoid paying international roaming fees to their own carrier and instead be able to swap in SIM cards from local providers.

As noted by Cult of Mac, Cut Your Sim announced a discontinuation of its unlocking service earlier this week after providing it to 400 customers. GSM Phone Source, which offered a similar jailbreak-free unlocking solution, stopped selling its own unlocker last week, citing poor turnaround times from its provider.

Both services say that those who already paid for the service are in the clear, but those with phones that hadn't yet been activated through Cut Your Sim's service will have to wait "a couple of days" to get a refund, according to a FAQ on the matter.

The moving parts behind the unlocking service were actually provided by a third party, a Cut Your Sim representative told Cult of Mac in an interview. "We are not sure where the service comes from, or whether it's a contact through AT&T or Apple. We do know that the service is performed in the U.K., but that's about it," the person said. A person familiar with the gray-market unlocking industry told CNET that several suppliers provide unlocking services that companies could then resell, but that most of those go through the same source.

Apple and AT&T did not immediately respond to a request for comment on whether they were actively involved in shutting down such operations.

Unlocking mobile phones that are on an active contract can be no small feat. Depending on where mobile subscribers are in their contract, what kind of plan they're on, and how long they've been a customer, carriers can facilitate an unlock. In Apple's case, this is a managed database that unlocks the matching phone when it's connected to iTunes. Both of the closed services made this possible by first collecting the customer's unique phone identifying number and then using a provider to get that information added to the system.

Despite the shutdown, Cut Your Sim says it's working on a follow-up iPhone unlocking service for select carriers.

"We do plan on offering iPhone unlocking services in the near future after we send out cancellations and refunds, but the service will be different, it will be for iPhones locked to certain carriers," the company said on its FAQ page. In an e-mail to CNET, a company representative elaborated on these plans, saying the cost would scale depending on the country where the iPhone originates.

"For some users, this is a cheaper option than the standard $169.99 fee, which guaranteed an unlock no matter what iPhone the carrier was locked to," the representative said. "Our carrier-specific iPhone unlocks start from $34.99 and go up to $174.99, depending on the carrier."