Where the facts come from.

Numbering plans

Country codes, exit (international) prefixes, trunk prefixes, number lengths, line types, example numbers and the places a number belongs to come from Google's libphonenumber metadata, through the PHP port giggsey/libphonenumber-for-php (version 9.0.41, Apache License 2.0). It is updated when the library is updated; numbering plans change a few times a year.

Time zones

Local times and daylight-saving changes come from the IANA time zone database as shipped with PHP. The time zones a number may be in come from libphonenumber's time zone mapping.

Country names

English country and territory names from the Unicode CLDR, via giggsey/locale.

Limits

A number can be correctly formatted and still be out of service; EZDial checks the pattern, not whether anyone answers. Some carriers use extra codes (for example a carrier-select code) that are not shown here. "A decent hour" means 8 AM to 9 PM in the other person's time unless you set other hours.

Typeface

Inter, by Rasmus Andersson and the Inter Project Authors, SIL Open Font License 1.1 (licence).