Send Bulk SMS on WhatsApp: Why Businesses Are Making the Switch

If your business already sends bulk SMS — promotional messages, appointment reminders, order updates, flash sale alerts — you are already comfortable with the idea of reaching many customers at once with a short, direct message. What most businesses discover at some point is that WhatsApp does everything bulk SMS does, and then significantly more, often at a lower cost per message and with dramatically higher engagement rates.

This guide is for businesses that have searched for "send bulk SMS on WhatsApp" — which typically means one of two things: you want to use WhatsApp as your bulk messaging channel instead of SMS, or you want to understand how WhatsApp compares to traditional SMS for this use case. Either way, this guide covers exactly that.

What It Means to Send Bulk SMS on WhatsApp

The phrase "bulk SMS on WhatsApp" reflects how most businesses think about mass messaging: you have a list of customer phone numbers, you want to send them all the same message (or a personalised version of it), and you want it to arrive immediately on their phones.

WhatsApp uses phone numbers as its addressing system, just like SMS. The difference is what gets delivered. Traditional SMS sends a plain text message with a 160-character limit (longer messages are split into segments and charged accordingly). WhatsApp sends that same message — plus images, videos, documents, and interactive buttons — through an internet-based channel that feels like a personal conversation rather than a marketing blast.

From the customer's perspective, a WhatsApp message from your business appears in the same app they use to message family and friends. It arrives with a notification, sits in a dedicated chat thread with your business name and logo, and can contain rich content. The open rates are dramatically higher than SMS, and critically, customers can reply — turning a one-way broadcast into a two-way conversation.

WhatsApp vs SMS for Bulk Messaging: A Direct Comparison

Before diving into how to set up bulk messaging on WhatsApp, it helps to see exactly where the two channels differ:

The open rate differential is the figure most businesses focus on: WhatsApp messages are read by 80–95% of recipients, compared to 20–35% for SMS. For a promotional campaign, this means roughly three to four times more customers actually see the message.

The cost comparison varies by market and by the type of messages being sent, but for businesses running high volumes in markets where WhatsApp penetration is high (India, Brazil, Southeast Asia, much of Europe, the Middle East, and Africa), the cost-per-engaged-customer is typically lower on WhatsApp than on SMS even when accounting for API access costs.

The one genuine advantage SMS retains is that it works without internet access. If your customer base includes people in areas with limited connectivity, SMS reaches them when WhatsApp cannot. For urban markets with reliable data connectivity, this is rarely a practical consideration.

How to Send Bulk Messages on WhatsApp (Step by Step)

The process differs from bulk SMS in one important way: WhatsApp requires official API access for any bulk sending beyond 256 contacts. You cannot simply upload a phone number list and hit send. Here is how it works in practice.

Step 1: Get WhatsApp Business API Access

Bulk WhatsApp messaging at scale requires the WhatsApp Business API (also called the WhatsApp Business Platform). The most practical route for most businesses is signing up with a WhatsApp Business Solution Provider (BSP) — a Meta-authorised company that has built a platform on top of the API.

BSPs like Greenbubble handle the WhatsApp Business Account (WABA) application, phone number verification, and API infrastructure on your behalf. You access all the API's capabilities through a no-code dashboard without building or maintaining the technical integration yourself. Setup typically takes 24–72 hours.

Step 2: Collect Opt-Ins

WhatsApp enforces a key requirement that SMS often does not: recipients must have explicitly opted in to receive messages from your business. This opt-in must happen outside of WhatsApp — through your website, checkout flow, in-store signup form, or SMS confirmation.

For businesses transitioning from SMS to WhatsApp, this is often the most significant workflow change. If you have an existing SMS subscriber list, you cannot simply import it into WhatsApp and start sending. You need to collect fresh WhatsApp opt-ins, typically by:

• Adding a WhatsApp opt-in checkbox alongside your existing SMS opt-in at checkout
• Sending an SMS campaign to your existing list inviting customers to opt in to WhatsApp updates (with a link to a landing page where they can confirm)
• Using your existing customer interactions — support calls, in-store visits, email newsletters — to invite WhatsApp opt-ins

Businesses that do this transition properly end up with a smaller but significantly more engaged WhatsApp list compared to their SMS list. Higher engagement rates and lower block rates make the WhatsApp list more valuable per contact over time.

Step 3: Create Message Templates

Unlike SMS, which allows you to send any text you want to opted-in contacts, WhatsApp requires that business-initiated messages use pre-approved templates. These are message formats you submit through your BSP for review by Meta before use.

A WhatsApp message template consists of:

• Body: your main message text, with {{1}}, {{2}} placeholders for personalised variables (customer name, order number, discount code, appointment date, etc.)
• Header (optional): a short text line, or an image, video, or document above the body
• Footer (optional): a short secondary line of text beneath the body
• Buttons (optional): up to three call-to-action or quick-reply buttons

Templates are categorised as Marketing, Utility, or Authentication, which determines their pricing and the approval criteria they are evaluated against. For promotional campaigns (the equivalent of bulk marketing SMS), use the Marketing category. For transactional messages (order updates, appointment reminders), use Utility.

Template approval typically takes a few hours to two days. Once approved, you can use the template in unlimited campaigns.

Step 4: Upload Your Contact List and Map Variables

In your BSP platform, upload the opted-in contact list for your campaign and map the personalisation variables in your template to the corresponding columns in your contact data. If your template uses {{1}} for first name and {{2}} for a discount code, you map those to the relevant columns in your contact file.

Good BSP platforms let you segment your list before sending — filtering contacts by tag, custom field value, purchase history, or last interaction date. Segmentation is one area where WhatsApp bulk messaging outperforms bulk SMS significantly: because you are sending through an API-connected platform rather than a carrier relay, you can maintain rich customer data alongside contact numbers and use it to target intelligently.

Step 5: Schedule and Send

Set your send time and launch. The BSP platform fires an individual API call per contact, personalises each message with the contact-specific variable data, and handles retries for any failed sends automatically. You do not manage carrier connections, message encoding, or segment splitting — those are SMS-era concerns that the WhatsApp API abstracts away entirely.

Unlike SMS, you can send messages with rich media (product images, promotional videos, PDF catalogues) without additional complexity on the sending side. The same campaign that would require a plain text SMS with a link can instead deliver the visual content directly in the message.

Step 6: Monitor Results

After sending, your platform shows real-time delivery and engagement data:

• Sent: accepted by Meta's servers
• Delivered: reached the recipient's device
• Read: the recipient opened the message (this data is available on WhatsApp in a way it is not on SMS)
• Replied: the recipient responded
• Failed: could not be delivered

The read-level data is the significant difference from SMS. With bulk SMS, you typically know only whether the message was delivered to the carrier; whether the customer actually read it is unknown. With WhatsApp, read receipts give you genuine engagement data to optimise future campaigns.

Use Cases: What Businesses Are Replacing SMS With on WhatsApp

Promotional Campaigns

Flash sales, seasonal offers, loyalty programme updates, and new product launches. These are the bulk SMS campaigns most businesses have been running for years. On WhatsApp, the same campaign delivers a higher open rate, can include product images or a promotional video, and features a button that links directly to the product or offer page rather than a plain URL in a text field.

Order and Delivery Notifications

Order confirmations, dispatch notifications, and delivery updates are high-value utility messages that customers actively want to receive. Transitioning these from SMS to WhatsApp adds read receipts (so you know customers actually saw the notification) and the ability to include a button for tracking or customer service.

Appointment Reminders

Healthcare providers, salons, consultancies, and any service business with scheduled appointments. WhatsApp appointment reminders can include quick-reply buttons — "Confirm", "Reschedule", "Cancel" — that make it easy for customers to act without calling or navigating to a booking system. The response data feeds directly back into your platform for automated follow-up.

Abandoned Cart Recovery

Customers who added items to their cart and did not complete checkout. A personalised WhatsApp message with the specific items they left behind, and a button to return to checkout, achieves higher recovery rates than the equivalent SMS. See our guide on WhatsApp abandoned cart recovery for the full setup.

Re-engagement Campaigns

Contacts who have not purchased or engaged in 30, 60, or 90 days. A personalised re-engagement message with a specific offer relevant to their purchase history performs significantly better than a generic bulk SMS blast because the channel feels more personal and the content can be visually differentiated.

Common Questions When Switching from Bulk SMS to WhatsApp

Do recipients need to have WhatsApp installed?

Yes. WhatsApp messages only reach people who have the WhatsApp app installed on their phone and active on the number you are messaging. In high-WhatsApp-penetration markets, this is rarely a practical limitation — for most customer bases in those markets, WhatsApp penetration is 85–95%+. In markets with lower WhatsApp adoption, SMS may still be necessary for contacts outside that group.

Can I keep sending SMS and WhatsApp in parallel?

Yes, and this is the most common transition strategy. Run WhatsApp for your opted-in WhatsApp list and retain SMS for contacts who have not opted in to WhatsApp, contacts in lower-penetration markets, or as a fallback for failed WhatsApp deliveries. Most BSP platforms can trigger an SMS fallback for contacts where the WhatsApp delivery fails.

Is WhatsApp bulk messaging cheaper than SMS?

It depends on your market and message volume. WhatsApp charges per conversation (a 24-hour window) rather than per message, which can be significantly cheaper than per-message SMS pricing when you have a back-and-forth exchange. For one-way broadcast messages with no replies, the per-conversation cost is effectively the same as a per-message cost. Platform fees add to the equation. For businesses in markets with expensive SMS rates, WhatsApp often comes out substantially cheaper at scale.

What is the character limit for WhatsApp bulk messages?

WhatsApp message template bodies support up to 1,024 characters. Free-form messages in an open conversation window allow up to 4,096 characters. There is no segment splitting — a 500-character WhatsApp message is one message, not three SMS segments.

Can I include images and videos in bulk WhatsApp messages?

Yes. WhatsApp templates support image, video, and document headers. Including a product image or a short promotional video in a bulk broadcast requires no additional sending infrastructure — you simply attach the media to the template when creating it in your BSP platform.

How do I handle replies to bulk WhatsApp messages?

Replies from customers come back into your platform's inbox. If you are sending to a large list, the volume of replies can be significant. A WhatsApp chatbot handles the majority of common responses automatically — answering FAQs, processing simple requests, routing to the right department — while complex queries route to a human agent via the shared team inbox. This is a capability that bulk SMS fundamentally cannot match without significant telephony infrastructure.

Do I need to re-verify contacts I already have on my SMS list?

Yes. An SMS opt-in does not constitute a WhatsApp opt-in under Meta's policies. Contacts must explicitly consent to receive WhatsApp messages from your business. You will need to run an opt-in collection campaign before messaging your existing SMS list on WhatsApp.

Making the Move: What to Expect in the First 90 Days

Businesses that transition from bulk SMS to WhatsApp typically go through a predictable pattern in the first three months:

Days 1–30: Collecting WhatsApp opt-ins from existing customers. Initial WhatsApp list is smaller than the SMS list — typically 30–60% of the SMS list size depending on how actively you promote the opt-in. First campaigns generate notably higher read rates than equivalent SMS campaigns, often prompting faster opt-in investment.

Days 30–60: First full promotional campaigns on WhatsApp. Read rates of 70–90% feel dramatically different from SMS. Reply handling setup becomes important — chatbot configuration to handle common responses to campaign messages. Greenbubble's no-code chatbot builder is designed for this stage specifically, letting you build response flows without developer involvement.

Days 60–90: Comparison data is clear. Cost per engaged customer is lower on WhatsApp for most businesses in high-penetration markets. WhatsApp list continues to grow as opt-in collection becomes a standard part of the customer journey. Most businesses at this stage are actively reducing SMS spend and reallocating to WhatsApp.

Send Bulk Messages on WhatsApp with Greenbubble

The mechanics of bulk WhatsApp messaging are closer to bulk SMS than most businesses expect — you have a list of phone numbers, a message you want to send, and a goal of reaching as many opted-in customers as possible. The difference is in the results: higher open rates, two-way conversation capability, rich media support, and genuine read-level analytics.

Greenbubble is an official WhatsApp Business Solution Provider with a purpose-built bulk broadcast feature that handles the complete workflow — contact management, template creation, segmentation, scheduling, and analytics — without requiring any technical setup on your end. Get API access through Greenbubble's guided onboarding, build your opted-in WhatsApp list, and run your first campaign in the same time it would take to set up a new SMS campaign.

Alongside bulk broadcast, Greenbubble includes a no-code WhatsApp chatbot to automate replies from your campaigns, a shared team inbox for conversations that need a human agent, and full campaign analytics to track performance and improve over time.

View Greenbubble's pricing plans and start sending bulk WhatsApp messages today — with the open rates that bulk SMS has never been able to match.