Hello,
I am integrating the MTN MoMo Remittance Sandbox API from a cloud-hosted server environment.
The integration previously worked successfully. We were able to:
- generate an OAuth access token;
- validate a Sandbox account holder;
- submit a Remittance transfer (
202 Accepted); - retrieve the transfer status as
SUCCESSFUL.
However, the OAuth endpoint is now being rejected:
POST https://sandbox.momodeveloper.mtn.com/remittance/token/
Instead of the documented OAuth JSON response, MTN returns:
- HTTP status:
200 - Content-Type:
text/html - Content-Length:
247 - message:
Request Rejected
A Support ID is also returned for the rejected request.
The issue appears consistent with a Sandbox WAF/network restriction affecting server-to-server requests from a cloud environment.
Could you please confirm:
- whether the MTN Sandbox WAF may be blocking our server requests;
- whether an outbound IP or IP range needs to be allowlisted;
- whether there are specific network/IP requirements for server-to-server access to the Remittance Sandbox API?
We can provide the MTN Support ID and relevant network information privately if required.
We will not share API keys, subscription keys, access tokens, API credentials, hostnames, or other sensitive information publicly.
Thank you.