A startup with financial backing from Deutsche Telekom and Intel, Jajah's user base has jumped from 2 million to 10 million in recent months, the startup reported.
"The partnership leverages Jajah's open, next generation communications platform to support the existing Yahoo Messenger voice offering beginning in the third quarter," Jajah said in a statement.
Yahoo Messenger users have been using Yahoo's "Phone in and Phone out" service for calls among landline phones, mobile phones, and PC connections. Jajah will take over the provisioning of the Yahoo service, including telephony infrastructure, payment processing, and customer care.
The Phone In and Phone Out service will let users make low-cost calls over Jajah's network to more than 200 global countries. PC-to-PC calls among service subscribers are free; there's a penny-a-minute charge for calls to U.S. landline and cell phones. A phone number can be acquired for $2.50 a month.
Jajah said it will soon announce business partnerships with some landline operators, cable companies, mobile carriers, and other technology partners. "Through our diverse managed service options and an open network, we are pleased to answer the call of our business customers and partners," said Trevor Healy, Jajah CEO, in a statement.
Jajah is perhaps best known for a service that customers can use to make inexpensive international calls. Customers enter two phone numbers into Jajah's Web site, the number they are trying to reach and their own number. Jajah then tries to call both numbers. Once both numbers answer, Jajah connects them to each other.