The API Preferences located here on your account allow you to set the preferences for API requests using your account. Specifically they do the following:
1. Default response format:
This lets you set the default response format you want API Calls to use - CSV, JSON, or XML, which dictates the format that will be returned on each API call. If you don't specify the specific response format to use within an API Call, this default from your account will be used. You can read more about response formats here.
2. Default response type:
This lets you set the default response type you want API Calls to use - Simple, Basic, or Extended, which dictates which fields will be returned on each API call. If you don't specify the specific response type to use within an API Call, this default from your account will be used.
3. Default country:
This setting lets you specify the country that you receive most of your phone calls from, which is typically the country you live in. This setting will attempt to resolve issues with Caller ID Numbers that are NOT formatted in E.164 format. Here's an example:
You set your default country to "United Kingdom". If you receive a call that includes the Caller ID Number "02079460000", this number is not in E.164 format, rather it is in a local UK format. In this case, TrueCNAM will attempt to convert this number to the correct E.164 number format, which is "442079460000" (IE adding the country code "44" in front, and removing the local format leading "0" in "0207...").
The Default Country feature cannot resolve all issues, and you should ensure you're always submitting all numbers in E.164 format to avoid issues with CNAM lookups and any other API Call.