US tower operator Crown Castle International has agreed to acquire privately held Lightower Fiber Networks for about $7.1 billion in cash, a deal that will make it one of the largest owners of metro fibre in the US.

Crown Castle, which is the largest provider of shared wireless infrastructure in the US with 40,000 towers and 50,000 small cell nodes on air, is buying Lightower from a group of investors including Berkshire Partners and Pamlico Capital.