Sprint on Wednesday reported its financial results for the first quarter of 2013, which saw the carrier’s subscriber base and service revenues grow to record highs. Unfortunately, the company still found itself in the red, posting a net loss of $0.21 per share, or $643 million, on sales totaling $8.8 billion. That’s a slight improvement over the same quarter last year, when Sprint posted a loss of $863 million. Wireless service revenue in Q1 2013 came in at $7.1 billion, the highest on record for Sprint.

“This is a transformative year for Sprint and we’ve gotten off to a good start,” said Dan Hesse, Sprint CEO. “Record Sprint platform service revenue and subscriber levels fueled our performance. We achieved significant Adjusted OIBDA growth while investing heavily to improve our network, expanding our 4G LTE footprint and offering customers the best smartphones with truly unlimited data plans.”

The carrier also noted that 86% of Sprint brand handset sales in the first quarter were smartphones (5 million units), including iPhone sales totaling 1.5 million units.