A recent text campaign by Unite the Union, the most reputed union of UK, delivered messages well beyond the planned hours. It was neither their intention nor their fault.
We felt compelled to address why or how it happened.
CallHub has a rate limit (for sending texts) which is standard across the platform for all customers across all their SMS campaigns.
However, every once in a while, we are tasked with campaigns that have strict timelines. To achieve that we selectively increase the rate limit so that we can achieve the target(delivering the messages to most of the recipients) within the stipulated time marked for the campaign to complete.
However, when the text goes out from CallHub’s system, it is on the service provider to deliver it to the recipients(phone numbers). The service provider adds those messages to their queue and sends them out as per their rate limit. Usually, this happens instantly as both the rate limits are in sync. However, when the CallHub rate limit exceeds the service provider’s, some messages get queued and sent when the queue frees up.
This was the case with Unite the Union campaign that delivered messages beyond 9 PM GMT. So, as configured by Unite the Union, the campaign on CallHub stopped sending any messages beyond that timeline. However, the CallHub rate limit was adjusted to deliver the most SMS by that time. This ended up having a lot of pending messages in the service provider’s queue. Those pending texts were then periodically sent well beyond the stipulated time. To stop the queued texts was beyond the control of Unite the Union or CallHub.
Although the frustration at the recipients’ end is well justified, it was absolutely not something Unite the Union intended or planned. They had no control over it.
The purpose of technology is to make things easier. However, in this instance, it was definitely not the case. We deeply regret the inconvenience that was caused due to these unforeseen events.
