America's third-largest carrier has posted yet another quarterly net loss. Its Q1 2013 results reveal a $643 million net loss on $8.79 billion revenue. It wasn't all bad news for the company, however, as it managed to generate a positive operating revenue of $29 million. Sprint is currently making big investments to upgrade its network for LTE and close its Nextel network, and is expected to continue posting net losses over this year.

The company sold five million smartphones over the quarter, 1.5 million of which were iPhones, and managed to add just 23,000 postpaid subscribers to its network — a 91 percent drop in additions year-over-year. When added to the continuing exodus of Nextel customers — 572,000 postpaid customers left the soon-to-be-defunct network, and only 263,000 re-signed with Sprint — it's clear that Sprint's customer base continues to dwindle. Sprint says the Nextel network, which only has 1.3 million subscribers left, is on track for shutdown by June 30th.

Sprint's LTE network has continued to roll out over the past three months, and it's now live in 88 cities — that's an addition of 30 cities over the quarter, including Los Angeles and Boston. It says LTE will be available to its customers in more than 170 additional cities over the coming months. CEO Dan Hesse says this is a "transformative year for Sprint and we’ve gotten off to a good start." The carrier is currently being courted by both Japanese carrier SoftBank and the Dish Network in a pair of entirely separate multi-billion dollar deals. Hesse will be talking analysts and investors through its Q1 2013 earnings in a conference call at 8AM ET today, and we'll be listening in to bring you any additional news.