Sprint (NYSE:S) MVNO Ting Mobile said that because of a system Sprint has implemented to check if a customer still owes the carrier money, some customers are experiencing difficulties in bringing their phones over to Ting and other Sprint MVNOs.

"Sprint's Financial Eligibility Check (FEC) that runs prior to a device being activated with an MVNO like Ting, has been very poorly implemented," Ting's Andrew Moore-Crispin wrote in a company blog post. "Customers of MVNOs are the ones bearing the brunt of this poor implementation. We are very sorry."

Moore-Crispin wrote that until recently Ting's bring-your-own-device program had been limited to devices that were compatible with Sprint's network and that Sprint had had in the market for over a year. However, following changes to its unlocking policy last week, Sprint lifted those restrictions, he wrote. The changes are likely due to Sprint's participation in an industry-wide effort to improve the handset-unlocking process for consumers. Click here for more on this story.

Under the new BYOD rules, Moore-Crispin noted, the only requirements are that "the device being brought to Ting be Sprint network compatible and also be in good financial standing with Sprint. That is to say, fully paid for, not reported lost or stolen and not tied to an account with an outstanding balance."

However, while that is a welcome development, Moore-Crispin wrote that the "bad news is that some devices that previously would have had no trouble coming to Ting are now being blocked from making the move, basically because the owner hasn't paid his or her final bill… most likely because they haven't actually received that final bill. Yeah."

"As it stands, if you bought a Sprint device on a contract, you will have to settle up your bill or any other outstanding balance with Sprint before we can activate the device on Ting," he added. "Until your final bill is paid in full, Sprint will block your device from being reactivated. This complicates things if you're looking to move your Sprint device to Ting at the same time you move your Sprint number to Ting. It's a classic (very annoying) catch 22."

In a statement to FierceWireless, Sprint said it has been working with its MVNOs since August 2014 to prepare them for the policy change, "which has proactively opened up access to a greater number of Sprint devices and better equipped our MVNOs to validate their availability prior to activation."

"Sprint provides our MVNOs an error code in the validation process to indicate if financial eligibility has not been met so that the customer can call and resolve their issues privately," the company said. "The bottom line is that a customer must contact Sprint if they have not satisfied their financial requirements before we can unlock a device or release their phone number."

"Since implementation, we have been evaluating this BYOD process for MVNOs and our functionality is working as designed," Sprint added.

Moore-Crispin noted that "just because your device is being rejected right now doesn't mean it can never be activated on Ting. You may just seeing the effect of this poor implementation."

Moore-Crispin added that even some unlocked devices that customers purchased directly from a handset vendor (including some versions of the Nexus 5 and 6, iPhone 6 and 6 Plus, Moto X and Moto G) are coming back as being "financially ineligible" from Sprint. "They are, quite obviously, not financially ineligible as they weren't purchased from Sprint," he wrote.

"Because of the poor implementation of this new Sprint program, we're not seeing data which would help us to determine which of these FEC rejections are valid catches of devices that do, in fact, still have some kind of financial obligation to Sprint, and which are being erroneously flagged despite the fact that Sprint has no claim on them," he added. "We're chasing down all the information we can get our hands on and we'll keep this blog post updated with the latest news as we get it. It's a much more sensible system all things considered."

Ting's public complaints against Sprint represent a rare clash between an MVNO and its host wireless carrier. However, Ting recently added support for GSM devices, likely through a partnership with T-Mobile US (NYSE:TMUS)--a move that may ease its reliance on Sprint.

For more:

- see this Ting blog post

- see this Prepaid Reviews post



Related Articles:

Sprint MVNO Ting doubled accounts in 2014 to 94,000

Verizon, AT&T, Sprint, T-Mobile and others now fully embrace cell phone unlocking rules

FreedomPop launches limited Sprint BYOD program, but iPhone remains MIA

MVNO Ting will not charge activation fee for BYOD program

Article updated Feb. 18 at 2:45 p.m. ET with a statement from Sprint.