US regional CDMA operator Alltel is rumoured to be up for sale. The rumour mill began grinding away late last week when executives said during the company’s fourth quarter results that Alltel was exploring its options.

Speculation that Verizon Wireless may be interested in the company is strong, given that both operators use CDMA.

Such a move would once again make Verizon the biggest operator in the US – a crown stolen from it by the merger of AT&T Wireless and Cingular Wireless in 2004.

According to Informa Telecoms & Media’s World Cellular Information Service (WCIS), Alltel had almost 12 million subscribers at the end of January. Verizon had 59.7 million and Cingular had 61.9 million. This means Verizon could take a clear lead in the market.

Of course, Sprint Nextel, which also operates a CDMA network, could also be interested in Alltel but it appears the company has enough on its plate already with the ongoing integration of Sprint and Nextel following its own merger.

If anything, it is the prospective price that might put Verizon, and any other operator, out of the picture. Some estimates have valued Alltel at around $30bn.