T-Mobile has enjoyed an undeniable head start in 5G in the US, thanks to its lucrative Sprint deal, and it’s turning some old spectrum around to pad out its lead. The company has deployed its 1,900MHz spectrum nationwide on its mid-band Ultra Capacity 5G network. The 1,900MHz band has a new lease on life after previously serving the now-defunct Sprint LTE and T-Mobile 3G networks.

T-Mobile used its 1,900MHz holdings in a past life to host 3G HSPA+ service while it built out an LTE network using 1,700MHz spectrum. This was also instrumental in making sure unlocked 3G iPhones could use T-Mobile’s network — the 1,700MHz spectrum it relied on for 3G wasn’t compatible with the iPhone. Meanwhile, Sprint used its 1,900MHz spectrum to build out an LTE network after failing to make WiMAX happen. Today, it’s all 5G. According to T-Mobile network SVP Mark McDiarmid, “The 1,900MHz PCS spectrum we’re deploying for 5G is being re-farmed from both 3G and 4G. The re-farm began after we integrated the T-Mobile and Sprint networks, so the assets came from both legacy networks.”

More recently, the 1,900MHz spectrum has also played a role in T-Mobile’s three-carrier aggregation, where it’s combined with two other mid-band channels to provide monstrously fast speeds. T-Mobile tested this technology earlier this year on its live network; now, it’s available to customers in “parts of the network.” Currently, you need a Samsung Galaxy S22 to take advantage of it, but the company plans to make three-carrier aggregation available nationwide and for more devices “in the near future,” all according to T-Mobile’s press release. When that happens, what’s old will truly be new again.