Random Phone Number Generator

Why phone validation is harder than it looks

The most common phone validation bug is assuming a fixed length. Germany does not have one — subscriber numbers vary, and a rule demanding exactly eleven digits rejects real numbers. The second most common is mishandling the trunk zero: most countries drop the leading zero when writing the international form, so 07700 900123 becomes +44 7700 900123. Italy is the exception that catches everyone, retaining the zero on landlines.

The third is assuming area codes still exist as a separate field. Spain abolished them in 1998 and Poland in 2009; both now use a flat nine-digit number. A form that asks Spanish users for an area code separately is asking an unanswerable question.

Reserved ranges for fiction

Several regulators set aside number ranges specifically so that films, documentation and demos do not dial real people. The NANP reserves 555-0100 through 555-0199. Ofcom reserves 07700 900000 to 900999 in the UK. ACMA reserves parts of 0491 570 in Australia. If your test data will ever be seen outside your team — in a screenshot, a demo video, or published documentation — those ranges are the responsible choice.

Dialling codes and number formats

Country code and national number shape for every supported country. N marks a digit; spaces, brackets and hyphens are the conventional written form.