A Custom HTTP Webhook gateway needs a success rule that matches the provider’s response. In SMS Manager, a successful HTTP response can become a Sent record even when you have not established phone delivery.

Understand the default rule

With Success contains (optional) blank, an HTTP success response counts as success. That can be unsuitable for an API that returns HTTP 200 for both accepted and rejected messages, with the real result inside its body. For example, an HTTP 200 response containing {"accepted":false} is not proof that the provider accepted a text.

The optional field narrows success to a literal substring in the response body, alongside HTTP success. It is case-sensitive text matching, including the relevant spacing. It is not a JSON-path expression, regular expression or later delivery callback.

Review the intended response

1. Open SMS Manager → Gateways and configure the intended Custom HTTP Webhook gateway.
2. Compare the provider’s documented accepted and rejected response bodies.
3. Set Success contains (optional) to a distinctive acceptance marker if that provider’s response supports a reliable literal check.
4. Save, then plan an intended delivery test separately.

A broad word that appears in both response examples can create a false positive. Equally, a marker with spacing different from the real response can report failure after acceptance. A provider requiring more complex response interpretation may need an adapter rather than a guessed substring.

Investigate the original attempt

Check History for the gateway, time, recorded status and redacted error. The custom gateway does not supply a structured provider message reference merely because its HTTP rule matched. Use the corresponding provider record when available.

Do not change the rule and immediately repeat an uncertain send. The first request may already have acted. Preserve the original outcome and reconcile it before a repeat. A Sent record, a passed URL check and a phone-delivery report answer different questions.

See the PD SMS Manager WHMCS guide for related tasks, or explore PD SMS Manager.