MetroPCS will be completely turning off its old CDMA network June 21, but customers still have time to upgrade to a GSM/HSPA+/LTE device.

MetroPCS Store

Pre-paid wireless carrier MetroPCS was acquired by T-Mobile in 2013 and now customers are being alerted that on June 21 their CDMA network will be shut down in favor of T-Mobile's faster GSM/HSPA+/LTE network. That means owners of smartphones that connect to that legacy network will be out of luck after that date.

MetroPCS is offering upgrade credits for those old phones in exchange for getting a new device that works on the GSM/HSPA+/LTE network. In some cases, the new phone will be free after those upgrade credits, instant discounts and rebates.

According to Fierce Wireless, MetroPCS has already shut down its CDMA network in several major markets in the US, with just three markets remaining. About 92 percent of its customers are now off the legacy network, but there are still a little less than 500,000 customers that have yet to move off CDMA.

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Source: MetroPCS, Fierce Wireless