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Tropo EU and US API differences

Tropo operates two different instances of the Tropo cloud: one with data centers located in the United States is intended for use all over the world. The other, with data centers located in Europe, is tuned for the unique data privacy laws in the European Union, and isolates all calls, logging, billing information, and other data to keep them inside the EU.

Applications written against the Tropo API will run the same regardless of the hosting location. However, there's a few minor differences in business rules and API capabilities that are highlighted here. You'll find that there are reminders of these differences sprinkled throughout the documentation wherever a difference occurs, but you can also refer to this page for a complete list of API differences.

Signup & Accounts is no longer available for new accounts. Your existing Tropo account will not be used in the EU environment. To ensure compliance with European data privacy laws, a completely isolated copy of Tropo is used, including the Tropo account and application database.

Account verification is not needed in order to enable your account for outbound calling and SMS in All accounts are enabled for outbound dialing and SMS.


The API server is and should be used in place of Documentation examples, sample code, or libraries you use for accessing the Tropo API may reference but should be changed in your code to use instead.


All of the same speech voices and speech recognition languages are available in each environment, but the defaults are different. The default voice for is Ava, a US English female voice and the default speech recognizer is en-us, for US-accented English. In the environment, the default voice is Serena, a UK-accented English female voice and the default recognizer is en-uk, for UK-accented English.

Dialing and Caller ID

Dialing a telephone number from requires the full number, including the country code and + prefix (known as +E164 dialing). In, if the + is omitted, Tropo will assume the number begins with a country code and add the +, unless the number is 10 digits. In that case, Tropo will assume the number is a US number and prepend +1 to the number.

Sending a text message from to a number outside the US requires a Canadian number on your application. In, an SMS-enabled number from any country can send a text message to any other country.

Caller ID for incoming calls to a Tropo number in will always be the full +E164 number. In, however, for backward compatibility reasons, caller ID for incoming calls does not include the country code if the Tropo number called is a US or Canadian number and caller's number is from the US, Canada, or other country that uses a +1 country code.

Phone Number Availability

The list of countries where and can provide phone numbers is different in each environment. See the International Dialing documentation or the Pricing pages on each site for an updated list of available countries. The available types and capabilities of numbers in each environment also vary by location, and the documentation and pricing pages list those as well.


Transcription is not available in Using Transcription in this environment will not return an error in your logs or cause your application to fail. However, the transcription you requested will never arrive. Applications needing to transcribe recordings can use a third party transcription engine. An example of how to use an external transcription engine can be found in the blog post Advanced transcription and analytics with Voicebase and Tropo.