Verizon may have ambitious plans to build out its own fiber network to support small cells, but T-Mobile is happy to outsource the digging to make deployment costs more manageable.

Speaking at the Wells Fargo 5G Forum this week, T-Mobile VP of Radio Network Technology and Strategy Karri Kuoppamaki said the Un-carrier carefully considered its options before settling on a small cell strategy that utilizes dark fiber for densification. Kuoppamaki explained T-Mobile works with a number of partners who provide the fiber, real estate, and manpower for the build outs while the Un-carrier supplies the equipment and facilitates municipal dialogs. The result is an overall cost structure that has been whittled down to a “manageable level,” he said.

“We work together in deploying those small cells. This strategy has worked for us really, really well,” Kuoppamaki commented. “Ultimately small cell deployments, or successful small cell deployments, depend on the cost structure, especially the backhaul piece. If you can do that by partnering up with the right people, and bring that cost down a fraction of the cost of a macro then it makes sense.”

According to Kuoppamaki, T-Mobile currently has about 15,000 small cells today, including 13,000 DAS nodes. The Un-carrier is on track to add “several thousand” more by the end of 2017, and has another 25,000 in the pipeline for the next few years, he added.

Kuoppamaki indicated those additions will come as part of T-Mobile’s network capacity management program, with a particular focus on denser population areas. But the deployments are also part of a broader industry push toward densification ahead of 5G.

SNS Research recently estimated global spending on small cells will hit more than $3 billion by the close of this year – a figure that is forecast to grow to $4.3 billion in annual investments by 2020.

In addition to standalone femtocell, picocell, and microcell platforms, SNS indicated small cells are also beginning to be deployed in a C-RAN architecture to leverage the benefits of resource pooling and multi-cell coordination. This trend is especially noticeable in the indoor and enterprise segments and among prominent vendors like Ericsson, CommScope, SpiderCloud, and Huawei.

SNS also noted that unlicensed and shared spectrum small cells are also beginning to gain traction. Shipment revenues in that segment have the potential to reach $240 million by the end of 2020, the firm predicted.