# 30017: Carrier network congestion

Log Type: CARRIER

Log Level: ERROR

## Description

This error indicates that the downstream carrier is experiencing high MMS traffic and isn't accepting the message request. The request is retried during temporary carrier congestion and `30017` is returned if the carrier still doesn't accept it.

### Possible causes

* The downstream carrier is experiencing congestion in MMS traffic.
* Your application is sending MMS traffic in bursts during a period when carrier MMS capacity is constrained.

### Possible solutions

* Send messages over a longer period of time instead of sending large bursts.
* If the traffic isn't time-sensitive, schedule messages with `ScheduleType` and `SendAt` to spread delivery more evenly.
* Review your MMS throughput and queueing strategy for the account and sender types you use so peak traffic doesn't add avoidable burst pressure.
* If you send high-volume messaging traffic, consider Traffic Shaping to prioritize critical messages and reduce sender-level congestion inside your messaging flow.

#### Additional resources

* [Account Based Throughput Overview](/docs/messaging/guides/account-based-throughput-overview)
* [Traffic Shaping](/docs/messaging/features/traffic-shaping)
* [Message Scheduling](/docs/messaging/features/message-scheduling)