Sprint is moving ahead with plans to deploy 5G service in nine cities in the first quarter of 2019, but warned its next generation network won’t extend outside of metropolitan areas if its proposed merger with T-Mobile US fails.

In a filing with the US Federal Communications Commission (FCC) responding to criticism of the deal from Dish and others, Sprint said it lacks the low-band spectrum resources to push 5G capabilities beyond cities. Without the benefit of T-Mobile’s 600MHz spectrum and rural tower sites, CTO John Saw noted Sprint’s 5G network will be limited to urban areas “for the foreseeable future”.

“Sprint must continue to devote its 800MHz and 1.9GHz spectrum to our 4G LTE and 3G CDMA networks, and will use these spectrum bands for 4G LTE beyond 2024. Sprint’s 5G service, therefore, will only utilise our 2.5GHz spectrum.”

Due to the limited propagation characteristics of the 2.5GHz band, Saw added the operator has “no current plans or capability to make Sprint’s 5G network blanket the entire geography of the United States or to cover as many areas of the country as New T-Mobile’s network”.

All told, Saw said Sprint expects its standalone 5G sites to have around 150 million POPs by 2020, around half of the 302 million current POPs.

Dish and others have accused Sprint and T-Mobile of overselling the benefits of their proposed merger in their public interest filing with the FCC. Dish pointed to T-Mobile and Sprint’s previously announced plans to launch 5G services on their own as evidence the merger isn’t necessary.