Informa Telecoms & Media said the number of mobile phone subscribers in West Africa swelled to 49.3 million at the end of 2006, rising faster than in other parts of the continent, where the market grew by 39 percent.
Around 66.6 million West Africans are expected to have a mobile by the end of 2007, the research group said.
Research analyst Thecla Mbongue said the arrival of new operators in Nigeria, Guinea and Ivory Coast had pushed down the price of calls and SIM cards and lured more customers.
The sheer size of Nigeria also drove growth in the region. Africa's most populous country is expected to become the continent's biggest mobile market by the end of 2007 with nearly 40 million subscribers, ahead of South Africa.
"West Africa is expected to continue to sustain a higher growth rate than the average for the continent over the next five years... mainly due to new market entrants," Mbongue said.
Africa's third-ranked operator Celtel, owned by Kuwait's MTC, last year snapped up Nigeria's number three mobile operator and has been investing heavily in rolling out a network there.
Tough competition in Nigeria with the continent's biggest operator MTN has helped cut prices and spur growth.
Demand for mobile phones is spurred in Africa by patchy fixed line infrastructure and tariff cuts, but still only about one in five Africans has a cell phone.
Informa expects mobile penetration on the continent to grow to about 34 percent by the end of 2011.