Bug fix: pacing changes for SMS messages with more than one segment per SMS message


When campaigns are configured to send messages at a given rate (messages per minute), the platform is currently not accounting for how many message segments may be contained within that message.

Messages per minute pacing will be adjusted for any SMS campaigns with messages over 160 character limit imposed by vendors.

Change Category


Change Context

US telephone carriers introduced a throughput limit on messaging over North American toll-free and 10DLCs (10 digit longcodes, AKA DIDs) to prevent abuse.

Our vendor implements this limit on SMS segments. When an SMS message is longer than 160 characters, it is split into segments which appear stitched together on your handset. Any traffic our vendor receives from us that exceeds this segments per second limit is subject to queuing and eventually error responses.

When we implemented a corresponding rate limit internally, we did not take the segment count into consideration. For example, we consider a 200 character message as a single unit contributing to the rate limit, whereas our vendor considers it as 2 units.

Change Impact

This is a bug fix to prevent customers' campaigns which have long messages running into lots of errors. There is no effect on campaigns consisting of messages within the 160 character limit. In other words, the impact of this change is only on those campaigns that would have encountered errors without this change.

SMS campaigns with messages over segment limit imposed by vendors will notice slow down in pacing with a corresponding decrease in errors. Campaign will send messages at the rate of messages per minute configured on the campaign by counting message segments per message instead of messages per minute when there is only one segment per message.

Date of Change

No sooner than April 6th, 2024

Impacted APIs

PUT /api/v2/outbound/messagingcampaigns/{messagingCampaignId}



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