When sending a Text-to-Speech message via boomAPI, it is possible to set both the language and accent used when the message is played to the recipient. The table below contains a list of all supported countries along with the value to pass against the 'locale' parameter. The lowercase value sets the language and the uppercase the accent required.
| Country | Locale |
| Australia | en-AU |
| Denmark | da-DK |
| Finland | fi-FI |
| France | fr-FR |
| Germany | de-DE |
| India | en-IN |
| Italy | it-IT |
| Netherlands | nl-NL |
| Norway | nb-NO |
| Poland | pl-PL |
| Portugal | pt-PT |
| Russia | ru-RU |
| Spanish | es-ES |
| Swedish | sv-SE |
| UK | en-GB |
| USA | en-US |