SMS is the default channel for automated follow-up in this kind of system. The reasoning is sound, but the statistics usually cited to justify it deserve more scrutiny than they normally get.
The figure you will see everywhere, and its problem
You will frequently read that SMS has a 98% open rate against roughly 20% for email. That 98% figure comes from vendor and industry surveys, not peer-reviewed research, and the methodology is rarely published. We hold research on this site to the standard of citing primary sources, so it is not a number we will stand behind.
What can be said with more confidence is directional rather than precise: a text message arrives on the lock screen of a device the recipient is usually holding, while an email lands in an inbox that is checked periodically and filtered aggressively.
Why the channel matters more than the open rate
For a missed-call reply, the relevant window is minutes. The published response-time research shows the odds of qualifying a lead collapsing between a five-minute and a thirty-minute response. A channel that reaches someone inside that window beats one that does not, regardless of whether the open rate is 98% or 70%.
There is also a practical asymmetry: a customer can reply to a text in four words while walking. Replying to an email is a task they defer.
Where email still fits
Email is better for anything that needs length, attachments, or a paper trail, detailed quotes, scopes of work, invoices, terms. SMS is for the time-critical exchange that gets the job into the diary. Most systems use both, for different jobs.
The compliance constraint
SMS reach comes with obligations that email does not have in the same form. Commercial SMS in Australia requires consent, sender identification, and a working opt-out under the Spam Act 2003. Details in the SMS compliance guide.
Note: This page is part of Clearline AI's research library. Where specific statistics are cited, the primary source is linked. Where a figure is an estimate, a modelled scenario, or industry-reported rather than peer-reviewed, that is stated explicitly.