Bulk SMS vs WhatsApp Broadcast: Which Campaign Works Better?

You have 2,000 customers, one offer and a budget. Do you send it as a bulk SMS or as a WhatsApp broadcast? The answer depends less on which channel is "better" and more on who is on your list, what the message needs to do and how much preparation time you have.

This guide compares the two side by side for Kenyan businesses running campaigns: reminders, offers, announcements and re-engagement. If you want the wider picture of the two channels for everyday customer service, start with WhatsApp vs SMS for business in Kenya.

What is the difference between bulk SMS and a WhatsApp broadcast?

Bulk SMS sends the same text message, optionally personalised, to many phone numbers at once from your registered sender ID. A WhatsApp broadcast sends an approved WhatsApp template message to many opted-in contacts from your verified business number.

Do not confuse a WhatsApp broadcast on the WhatsApp Business Platform with the broadcast lists in the free WhatsApp Business app. App broadcast lists are small, sent from a phone, and only delivered to people who have saved your number in their contacts. Our article on WhatsApp groups vs broadcast lists vs channels explains those app features.

How do bulk SMS and WhatsApp broadcasts compare?

Which one reaches more of your list?

Bulk SMS reaches more people on almost any Kenyan list. A sender ID message goes to every active number on Safaricom, Airtel and Telkom, including the large share of phones that are not smartphones. Our Kenya SMS statistics page has the current figures from the Communications Authority.

A WhatsApp broadcast only reaches contacts who use WhatsApp and have agreed to hear from you. On a list of school parents in Kitui, that might be a minority. On a list of online shoppers who first messaged you from an Instagram ad, it might be nearly everyone. Look at your own contacts before deciding.

Which one gets more response?

WhatsApp usually produces more conversation, because customers can reply, tap a button or open a photo without leaving the chat. A broadcast for a Mombasa furniture shop can show the sofa, list the price and add a "Reserve one" button. Replies arrive in your shared inbox, where an agent can close the sale.

SMS works best when the action is simple and offline: "Pay via Paybill 123456", "Show this SMS at the till" or "School closes Friday at noon". When you need replies, add a WhatsApp number to the SMS so interested customers can start a chat.

We do not quote average open or response rates here, because published figures vary widely and are rarely measured on Kenyan audiences. Run both on a slice of your own list and compare the delivery reports and replies.

How much does each campaign cost?

Work it out per recipient. For SMS, multiply the number of recipients by the number of SMS parts in your message and by KES 0.55. A message of 161 to 306 characters counts as two parts, so trimming a few words can halve the cost.

For a WhatsApp broadcast, multiply the number of recipients by the price of the template category. On chat.or.ke, a marketing template costs KES 4.50 and a utility template, such as a payment reminder, costs KES 0.90. Length does not change the WhatsApp price, so you can include detail and an image at no extra charge.

The pricing page has a calculator for both, and contacts who opted out are skipped before sending, so you are not charged for them.

Which one is faster to launch?

Bulk SMS, once your sender ID is approved. You can write a closure notice at 7am and have it on every parent's phone minutes later. Sender ID registration itself takes time the first time: Safaricom reviews applications in twice-weekly batches and the other networks usually take one to two weeks. See sender ID registration for the documents.

WhatsApp broadcasts need an approved template. If the template already exists in your library, sending is just as quick. A brand-new promotion needs Meta's review first, which is often quick but can be rejected if the wording breaks the rules. Keep a few general templates approved in advance, such as "new stock", "event reminder" and "payment reminder", so you are never waiting.

Which one carries more risk?

Each channel has a different failure mode. With SMS, the main risks are cost surprises (emoji and long messages) and complaints from people who never agreed to receive promotions, which can lead to ODPC action under the Data Protection Act.

With WhatsApp, the main risk is your number's reputation. When many recipients block or report a broadcast, Meta lowers your quality rating and can restrict how many people you may message. Our guide on sending WhatsApp broadcasts without getting blocked covers the habits that protect a number.

Which should you choose?

Pick by audience and message, using these rules of thumb:

SMS is the honest better fit when your audience is broad, older or rural, when the message is a notice rather than a pitch, or when you cannot wait for template approval. WhatsApp is the better fit when your customers already chat with you there and the campaign is meant to start conversations.

How do you send the same campaign on both channels?

Keep one contact list and split it by channel. In chat.or.ke, contacts carry tags and segments, so you can tag WhatsApp users who opted in and send them a WhatsApp broadcast, then send the SMS version to everyone else with bulk SMS. Opt-outs are shared, so a customer who replied STOP on WhatsApp is not messaged by SMS either.

Write the two versions separately. The SMS should be under 160 characters with one clear action. The WhatsApp template can add a photo and a button. For ready-made wording, see our bulk SMS templates for Kenyan businesses.