A phone number validator that cleans dialler lists

The phone number validator inspects each number against the official numbering rules for its country. It strips the inconsistent formatting real lists are full of — spaces, dashes, brackets, missing or doubled country codes — and works out whether what remains is a genuine, diallable number.

For every valid number it returns the country, the line type, and two clean formats: E.164 for software and tools, and the national format for humans. Line type matters for outreach — knowing a number is a mobile tells you it can take an SMS, while a landline or VOIP line cannot.

Numbers that cannot be made valid are flagged with a reason rather than silently dropped, so you can see exactly which rows need attention. The result is a list that imports cleanly into a dialler or SMS platform on the first try.

Validation also protects the tools downstream. Most diallers and SMS platforms reject or silently drop malformed numbers on import, which means a messy list quietly loses contacts before the first call is ever placed. Running the phone number validator first means every row that reaches your dialler is already in a format it accepts, already tagged with a country, and already sorted into mobile and landline. For teams that work several countries at once, that consistency is the difference between a clean campaign and an afternoon spent reconciling formats by hand. The job also returns a clear count of how many numbers were valid, so you can judge a source list at a glance.

• Sales teams cleaning a phone column before it is imported into a dialler or power-dialling tool.
• SMS marketers filtering a list down to mobile numbers, the only lines that can receive a text.
• RevOps standardising messy international numbers into a single consistent format across a CRM.
• Support teams validating customer phone numbers at the point of import to cut failed callbacks.

Each input number returns a validity flag, country, type and clean formats:

The phone number validator applies the same numbering metadata that powers carrier and operating-system phone handling — the length rules, prefixes and ranges each country defines. It parses a number, normalises it, and checks it against those rules to decide validity, country and line type.

Because it works from numbering rules rather than placing a call, the phone number validator is fast and runs entirely on a list — no external lookups, no waiting on a network. A large file is processed almost instantly and downloaded with every column added.