Check a Cameroonian number

The rule, in one line

A Cameroonian mobile number is nine digits long and starts with 6, preceded by the +237 country code in international form. Landlines start with 2 and are not accepted for sending. Everything else — spaces, hyphens, brackets, a 00237 prefix — is presentation, not the number.

What the API accepts, and what it turns down

The tool above is deliberately more forgiving than the API: it also strips hyphens, dots and brackets, because address books are full of them. The API only strips spaces.

A rejected number gets an explicit answer, and no debit:

HTTP/1.1 400 Bad Request

{
  "code": "INVALID_NUMBER",
  "message": "Numéro invalide : formats acceptés +2376XXXXXXXX, 2376XXXXXXXX, 6XXXXXXXX"
}

The call concerned is POST https://api.sms.gworldship.com/v1/sms; the number is checked before the balance, so an invalid number costs nothing. Error messages come back in French, error codes are stable and machine-readable — match on code, never on message.

Cleaning up a contact file

The same rule fits in a few lines, ready to run over a whole column before any import. It returns the E.164 form, the only one worth storing: it is what the API returns, and what to deduplicate on.

/** Cameroonian number in E.164, or null if it is not a mobile. */
function toE164(raw) {
  const cleaned = String(raw).replace(/[\s.\-()]/g, '');
  const national = cleaned.startsWith('+237')
    ? cleaned.slice(4)
    : cleaned.startsWith('237') && cleaned.length === 12
      ? cleaned.slice(3)
      : cleaned;
  return /^6\d{8}$/.test(national) ? '+237' + national : null;
}

// Deduplicate on the E.164 form: the same contact often shows up twice,
// once as "690000000" and once as "+237690000000".

What a format check does not guarantee

A well-formed number is not a reachable number. It may match no active line, or a handset that has been off for weeks. The only proof of arrival is the DELIVERED status reported by the carrier after the send; a message ending in FAILED is automatically refunded in credits.

Carrier detection reads an allocated range: it says nothing about a line having changed hands. For a campaign, sending and reading the statuses beats trying to validate everything upfront.

Frequently asked questions