Bandwidth
When using the MM4 interface for sending messages, error codes in the X-Internal-Status-Code field of MM4_Forward.RES or MM4_Delivery_Report.REQ may indicate issues. However, comprehensive visibility into MMS message status requires requesting a delivery receipt (DLR). Most errors are only accessible in MM4_Delivery_Report.REQ when a DLR is requested. To receive this report, enable the X-Mms-Delivery-Report field in MM4_Forward.REQ. Bandwidth will forward MM4_Delivery_Report.REQ from downstream carriers to the sender upon request.
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Twilio
If your SMS or MMS messages aren't being delivered, this guide helps troubleshoot the issue. Twilio usually responds with a 201 Created when processing your message request, visible in Programmable Messaging logs. If absent, there might be an API request problem or a Twilio incident. Check the Status Page for ongoing issues, resend the message, and monitor using REST API or Console's API Explorer.
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