# Guides to verifying and cleaning phone number lists

Practical guides on number validation and WhatsApp, Viber, RCS, iMessage and Telegram checks: how they work, when to use them and how to read the results.

How to tell which numbers are valid, which channels your contacts can actually be reached on, and how to use the results to lower campaign costs. Every guide explains the check, the possible outcomes and the most common mistakes.

## Guides

- [Phone number validation and HLR lookup: how to clean a database](https://numerovero.online/en/guides/phone-number-lookup-validation.md): What mobile number validation (HLR lookup) is, which outcomes it returns, what it costs in credits and how to use it to clean a database before campaigns.
- [WhatsApp number checker: find out in bulk which contacts you can reach](https://numerovero.online/en/guides/whatsapp-number-checker.md): How the WhatsApp check works on bulk number lists: outcomes returned, credit cost (1 per number), accepted file formats and mistakes to avoid.
- [Viber number checker: find out in bulk which contacts you can reach](https://numerovero.online/en/guides/viber-number-checker.md): How the Viber check works on bulk number lists: outcomes returned, credit cost (1 per number), accepted file formats and mistakes to avoid.
- [RCS number checker: find out in bulk which contacts you can reach](https://numerovero.online/en/guides/rcs-number-checker.md): How the RCS check works on bulk number lists: outcomes returned, credit cost (2 per number), accepted file formats and mistakes to avoid.
- [iMessage number checker: find out in bulk which contacts you can reach](https://numerovero.online/en/guides/imessage-number-checker.md): How the iMessage check works on bulk number lists: outcomes returned, credit cost (2 per number), accepted file formats and mistakes to avoid.
- [Telegram number checker: find out in bulk which contacts you can reach](https://numerovero.online/en/guides/telegram-number-checker.md): How the Telegram check works on bulk number lists: outcomes returned, credit cost (3 per number), accepted file formats and mistakes to avoid.

> Results describe the technical status detected at the moment of the check. They are not marketing consent and do not guarantee message delivery.

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