SoyMomo works in any country with 2G coverage. In general, the only countries that do not have 2G networks are Japan and Australia. We recommend checking with your local carrier or our list of recommended carriers.
In case of travelling to another country, you can enable the roaming feature on your SIM or buy a prepaid SIM in the destination country. Remember, SoyMomo needs to have signal and balance (calls and data) to work properly.