Top domestic carrier Verizon (NYSE:VZ) Wireless recently said it had completed its 4G LTE network rollout, which now covers 500 markets and 99% of its 3G footprint. No. 2 rival AT&T (NYSE:T) is still behind in terms of coverage, but Ma Bell is catching up.

AT&T just added another 35 LTE markets today, bringing its total tally up to 326. That's enough to cover 292 million people in its 4G network, but remember that AT&T includes HSPA+ in its 4G marketing claims. Only 200 million of these are covered by LTE specifically, and Ma Bell is targeting 300 million by the end of next year.

Smaller carriers Sprint and T-Mobile are still far behind the bigger two in the LTE race. Sprint just finally shut down its older iDEN network at the end of June in order to pave the way for more LTE capacity. The No. 3 carrier expects to repurpose its 800 MHz spectrum for LTE through next year. T-Mobile is far behind with LTE coverage, currently covering only seven markets.

The next transition that carriers will embark upon is launching Voice-over-LTE, or VoLTE. AT&T is planning to adopt VoLTE later this year, which would be just ahead of Verizon's VoLTE launch that Big Red delayed into 2014. However, since AT&T's network is built using a wider range of technologies relative to Verizon's, it won't be able to move toward LTE-only devices any time soon.

Verizon is hoping for LTE-only phones to help reduce costs and subsidies, and Big Red is closer to making this switch since its LTE network is complete. AT&T will rely on phones that need numerous modems for the foreseeable future.

AT&T may be starting to catch up, but it still has a long ways to go.

Fool contributor Evan Niu, CFA, owns shares of Verizon Communications. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.