Japanese number-one operator NTT Docomo announced that it has hit the 4 million subscriber milestone for its LTE network.

Docomo’s Xi network provides theoretical peak downlink speeds of 75 Mb/s and passed the 4 million subscriber mark on 22 July, around one and a half months after reaching 3 million subscribers.

According to the operator, the pace of new subscriptions nearly doubled following the introduction of a wider range of smartphones compatible with the Xi network earlier in the summer.

Docomo said it will aim to continue to strengthen customer satisfaction through related services such as Xi Talk 24, which offers Xi subscribers free and unlimited voice calls to all the operator's customers, as well as the further introduction of Xi-compatible smartphones, mobile Wi-Fi routers and other devices.

Docomo’s announcement follows South Korea’s SK Telecom, which revealed yesterday that it has hit the same LTE subscriber base. SK said this “solidifies” its position as the world’s second-largest LTE service provider behind Verizon Wireless. According to Wireless Intelligence, the US number-one has more than 9.8 million LTE connections.