Colombia and Venezuela are first on the list for handsets running Mozilla's operating system as its expansion takes it beyond Europe for the first time.
After launching in Europe earlier this year, Firefox OS has now landed in Latin America.
Telefonica's local brands in Colombia and Venezuela started selling two Firefox OS phones on Thursday: the Alcatel OneTouch Fire and ZTE Open.
In Colombia, the devices cost 199,900 pesos ($105) on prepay or 99,900 pesos on a 12-month contract at 39,900 pesos per month. In Venezuela, the Fire is priced at VEF Bs 1,739 ($275) and the ZTE Open at Bs 1,159.
Thursday's launch sees the number of countries where Firefox OS devices are available rising to four, following the arrival of the handsets in Spain in early July and the Fire in Poland later that month. Germany and Greece will be the next European countries to get the handsets, and Mozilla said Thursday that Telefonica expects to launch Firefox OS devices in Brazil in the fourth quarter.
Read more of "Firefox OS devices land in Venezuela, Colombia" at ZDNet.