T-Mobile USA had previously said it would explore the sale of its 37,000 wireless towers in an effort to make the company more financially independent of its parent Deutsche Telekom after its attempt to sell T-Mobile USA to rival AT&T Inc failed last year due to regulatory opposition.

T-Mobile USA's Chief Technology Officer, Neville Ray, told Reuters on Monday that the company had received the most interest so far from companies that are already in the business of operating wireless towers.

Analysts expect tower operators including American Tower, Crown Castle and SBA Communications to take a look at the assets and some had estimated a deal price of $2 billion to $3 billion.

But Ray, who would not name any potential buyers, said the evaluation process is still in the "very early days" and that it is too early to tell what price the towers might fetch.

Also on Monday, the executive announced T-Mobile USA's plan to buy network equipment from Sweden's Ericsson and Nokia Siemens Networks for a $4 billion network upgrade it is planning for 2013.

T-Mobile USA, which already uses Ericsson and Nokia Siemens equipment for its current network, did not disclose the value of the contracts with each vendor.

Ray said that the equipment contracts would take up a "significant portion" of the $4 billion budget.

It expects the two vendors to install equipment in all the 37,000 cell towers in its network for its upgrade to a faster-speed wireless data service.

Since the $39 billion AT&T deal fell apart last year, T-Mobile USA is having to scramble to catch up with high-speed wireless upgrades at its bigger rivals, including AT&T.

T-Mobile USA is following its rivals' footsteps by moving to a high-speed technology known as Long Term Evolution (LTE). Equipment vendors are expected to see a revenue boost as carriers around the world invest in upgrading to LTE.

Ericsson is the market leader in wireless network equipment and is double the size of its nearest rivals, Nokia Siemens and Huawei Technologies. Nokia Siemens is a venture of Finland's Nokia and Germany's Siemens.

(Reporting By Sinead Carew; Editing by Richard Chang)

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