SMS vs email vs phone follow-up: which books more calls?

No public study compares SMS, email and phone on booked calls per lead, so nobody can honestly name a winner. The published inputs point to a sequence: only 19% of US adults generally answer calls from unknown numbers (Pew), and Mailchimp’s average email click rate is 2.62%. Text to open, call to convert, email to document.

• Phone: in a Pew Research Center survey of US adults (July 2020), about eight in ten said they generally don’t answer calls from unknown numbers. 67% said they don’t answer but do check voicemail.
• Email: Mailchimp’s benchmarks (last updated December 2023) put the all-user average at 35.63% opens and 2.62% clicks. Mailchimp notes that Apple Mail Privacy Protection affects open rates.
• SMS: no independent read-rate or reply-rate benchmark exists. Twilio lists US$0.0083 per outbound long-code text plus carrier fees.
• Cost per 1,000 leads (worked model below): about US$1,340 for SMS-only, US$7,750 for phone-only and US$3,551 for a mixed sequence, on stated assumptions.
• The decision rule: a phone-only sequence has to book about 5.8 times as many calls as SMS-only to match its cost per booked call.

Which follow-up channel books the most calls?

Which follow-up channel books the most calls has no published answer, because no public study measures SMS, email and phone on the same denominator. That denominator is booked calls per lead contacted. Each channel reports a different number: email reports opens and clicks, phone reports answered calls, and SMS platforms report replies. A comparison across those three numbers is a comparison of three different things.

What can be compared is what each channel is good at and what each attempt costs. On those, the channels do different jobs. SMS gets a reply cheaply, a call turns an engaged lead into a booking, and email carries what the lead needs to read. The quotable version: SMS vs email vs phone is the wrong question, because the order you use them in decides the booking rate.

How should you compare SMS, email and phone follow-up?

Compare follow-up channels on six criteria, in this order, before you look at any open-rate claim:

1. Reach: will the lead see the message at all, from a sender they don’t know?
2. Reply speed: how quickly can a conversation start?
3. Booking inside the channel: can the lead pick a time without leaving it?
4. Cost per attempt: message fees plus the staff minutes each attempt takes.
5. Consent and compliance burden: what the law in the lead’s country requires before you send. Our TCPA guide for AI voice and SMS covers the US.
6. Depth: can it carry a price list, a proposal or a case study the lead will forward to a partner?

SMS vs email vs phone: what the published numbers say

The table below puts the three channels side by side using only figures published by the source named in each cell. Where no credible public figure exists, the cell says so.

Our AI SMS outbound automation guide explains why we don’t use the widely repeated 98% SMS open rate.

What does a seven-touch follow-up cost per 1,000 leads?

A seven-touch follow-up sequence costs very different amounts depending on the channel mix, and almost all of the difference is staff time, not message fees. The model below uses stated assumptions, not measured results. Replace each one with your own figures.

• Staff cost US$30 an hour, loaded (assumption).
• Two minutes of staff time per dial attempt, including voicemail and notes (assumption).
• Ten minutes per lead who engages, by call or text thread (assumption).
• Engagement: 25% of leads reply to SMS-only, 15% answer phone-only, 30% engage with the mixed sequence (assumptions).
• SMS at US$0.0083 plus the US$0.0045 T-Mobile carrier fee, so US$0.0128 a text (Twilio’s published US rates, read 2026-10-05). Email at US$0 marginal cost.

That last row is the decision rule. On these assumptions, a phone-only sequence has to book about 5.8 times as many calls as SMS-only to cost the same per booked call, and a mixed sequence about 2.7 times. If the mixed sequence books three times what SMS-only does, it is the cheaper way to fill the calendar. Run your own numbers through the same rows.

Should you call or text a new lead first? A decision table by situation

Whether to call or text a new lead first depends on how old the lead is, what time it is, and what the lead asked for. The table gives a starting rule for each situation. The thresholds are rules of thumb, not published benchmarks.

A home-services firm whose quote requests arrive at 8pm should start with SMS. A consultancy whose enquiries come in at 10am, with a partner free to call, should pick up the phone. The same firm can be in both rows in the same week.

Who each follow-up channel is wrong for

• SMS is wrong for leads who haven’t consented to texts, landline numbers, and anything longer than a few lines: a proposal squeezed into texts reads as spam.
• Email is wrong for speed. A lead who enquired five minutes ago and hears back by email is waiting in an inbox while a competitor calls.
• Phone is wrong for teams with nobody free when leads arrive, for after-hours leads, and for leads who asked not to be called. It is also the most expensive attempt by a wide margin.

If your booking rate is low whatever the channel, the problem is usually coverage or follow-up depth rather than channel choice. Our page on how to increase your sales call booking rate covers those levers.

When should you hand multi-channel follow-up to someone else?

Hand multi-channel follow-up to a done-for-you service when the mixed sequence is clearly the right answer but you can’t staff it. In the model above it takes about 117 staff hours per 1,000 leads, much of it in the evenings and at weekends when leads arrive, and calls, texts and email have to run as one conversation rather than three tools. That is when pay-per-result beats hiring.

Do it yourself if your leads arrive mostly in office hours, your volume is low enough for one person to call every new lead within minutes, or you only need the SMS-only sequence, which needs about 42 staff hours per 1,000 leads in the model.

The facts about LeadsNow, stated plainly: we book calls using AI calling, SMS and DM follow-up through our AI appointment setting service. You pay on results: a revenue share, a fee per appointment, or a mix of both. No-shows aren’t charged. There is no retainer, and you can cancel any time with 14 days’ notice. Since 2017 we have booked 50,769+ AI-booked sales appointments and generated 1M+ leads.

Frequently asked questions

Is SMS better than email for lead follow-up?

For a fast first reply, usually yes. For carrying detail, no. There is no independent benchmark that compares the two on booked calls per lead, so treat any single winner with suspicion and test both on one cohort of your own leads.

Do people still answer sales calls from unknown numbers?

Mostly not. In Pew Research Center’s 2020 survey, about eight in ten US adults said they generally don’t answer their mobile when an unknown number calls. 67% said they check the voicemail, so a short voicemail followed by a text still reaches most of them.

What is a good email open rate for follow-up emails?

Mailchimp’s benchmarks put the all-user average at 35.63% opens and 2.62% clicks, last updated December 2023. Mailchimp notes that Apple Mail Privacy Protection affects open rates, so clicks and replies are the safer measure.

Should I call or text a new lead first?

Call first if the lead is under five minutes old and someone is free to call. Text first after hours, at weekends, or when no one can call within minutes. Either way, use the other channel straight after if the first gets no answer.

How many follow-up touches should a sequence have?

There is no published standard. The model on this page uses seven touches across about two weeks. Stop any channel immediately when the lead opts out of it.