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When a customer needs an update, the channel you choose affects whether the alert reaches them, how quickly they notice it, and what they can do next.
A push notification may be ideal for someone actively using your app. SMS can reach customers without an internet connection. WhatsApp supports richer, two-way communication, while RCS can turn a simple alert into an interactive branded message.
But these channels are not interchangeable. Each has different requirements, reach, capabilities and limitations.
This guide explains what push notifications are, how they work, and how they compare with SMS, WhatsApp and RCS. It also looks at which channel makes sense for different types of customer alerts.
Use push notifications for customers active in your app, SMS for broad reach without an app, WhatsApp for two-way conversations, and RCS for rich, branded alerts on supported devices. Choose by customer access, urgency and the action needed, and add a fallback that checks delivery status first.
What Are Push Notifications?
Push notifications are short messages sent by an app or website to a user's device. They can appear on a phone's lock screen, notification centre, desktop or browser, even when the app or website is not currently open.
For example, a banking app might send a notification when a transaction takes place. A shopping app could notify a customer when an order is out for delivery. A website might send an update when an item on a user's wishlist is back in stock.
Push notifications are generally divided into two types:
1. App push notifications
These are sent by a mobile application installed on a user's device. The app's server sends a notification through the relevant platform notification service, such as Apple Push Notification service (APNs) or Firebase Cloud Messaging (FCM).
The user needs the app installed and must allow notifications. On iOS, the app must request permission to show alerts, play sounds or display badges. On Android 13 and later, apps generally need the user's runtime permission to send non-exempt notifications.
Apple's developer guidance says an app must ask permission before it can display alerts, play sounds or badge its icon (WWDC20 push notifications primer). Android documents the POST_NOTIFICATIONS runtime permission for non-exempt notifications from Android 13 (Android notification permission).
2. Web push notifications
These are sent by a website or web application through a browser. A user subscribes to notifications, and the website can send updates without requiring a separate mobile app.
Web push relies on browser technologies such as the Push API, Notifications API and service workers. On iOS and iPadOS, web push is supported for web apps added to the Home Screen from version 16.4 onwards.
Apple says Web Push for Home Screen web apps needs a user action, such as tapping a subscribe button, before the permission prompt appears (WebKit announcement).
The important distinction is that push notifications depend on an app or a supported web experience. They are not the same as SMS or messaging-app notifications.
What Does Push Notification Mean? And What Is a Push Notification Badge?
The meaning of push notifications is simple: a business or application sends a timely update to a device that has subscribed to receive it.
A push notification badge is a visual indicator, often a small number or dot displayed on an app icon, showing that there is new activity or something waiting for the user.
For example, a banking app may display a badge when there are unread account updates. A shopping app may show one when an order status has changed.
Badges are not separate messages. They are a visual part of the notification experience, and their appearance and behaviour depend on the device and app settings.
Push Notifications vs SMS vs WhatsApp vs RCS
All four channels can deliver customer alerts, but they work differently. The right choice depends on the customer's access, the urgency of the message and whether the customer needs to take an action.
Each card below lists the same six points for one channel, so you can read a channel on its own or compare the same line across cards.
Push notifications
- Requires an app?
- Yes for app push; web push requires a supported browser or installed web app
- Requires internet?
- Yes
- User permission or setup
- Notification permission and app/web subscription
- Rich media
- Supported, depending on platform
- Two-way interaction
- Usually through the app or website after opening
Best suited for: App engagement and timely in-app updates
SMS
- Requires an app?
- No
- Requires internet?
- No mobile data required, but mobile network service is needed
- User permission or setup
- No app installation; applicable messaging consent and regulatory requirements still apply
- Rich media
- Limited; SMS is text-based
- Two-way interaction
- Limited; depends on the SMS setup
Best suited for: Broad-reach alerts and essential updates
- Requires an app?
- Yes
- Requires internet?
- Yes
- User permission or setup
- Business messaging must follow WhatsApp policies and applicable opt-in requirements
- Rich media
- Images, documents, buttons and interactive content
- Two-way interaction
- Supports conversational replies
Best suited for: Conversational alerts and customer actions
RCS
- Requires an app?
- Requires an RCS-capable device and supported messaging service
- Requires internet?
- Generally requires data connectivity
- User permission or setup
- Availability depends on device, network and RCS support
- Rich media
- Rich cards, images, suggested actions and other interactive features
- Two-way interaction
- Supports replies and interactive experiences where enabled
Best suited for: Branded, interactive alerts
Related reading: Helo.ai's guides to WhatsApp vs SMS notifications and what RCS messaging is.
1. Push Notifications: Best for App and Website Engagement
Push notifications are useful when a business has an established app or web audience and wants to bring users back to a digital experience.
Common use cases:
- Banking apps notifying users about account activity.
- Retail apps sharing order and delivery updates.
- Travel apps sending check-in reminders or schedule changes.
- Websites notifying subscribers about new content or price changes.
The biggest advantage is that push notifications can reach users without requiring them to open the app first. They can also take users directly to a relevant screen when tapped.
However, reach depends on the user having the app installed or being subscribed to web push. Notifications can also be disabled at the device or app level. A business should not assume that installing an app automatically means a customer can be reached through push.
2. SMS: Best for Broad Reach and Essential Alerts
SMS remains useful when a business needs to reach customers across a wide range of mobile devices without asking them to install an app or use a messaging platform.
An SMS can be delivered without mobile data, although the recipient still needs an active mobile connection and SMS service.
Common use cases:
- OTPs and authentication codes.
- Payment confirmations.
- Appointment reminders.
- Service disruption and outage alerts.
- Transaction and account updates.
SMS is particularly useful for time-sensitive, concise information. It can also act as a fallback when a customer cannot be reached through a richer messaging channel.
For businesses sending bulk SMS in India, regulatory requirements matter. TRAI's framework includes Principal Entity registration, registered headers and content templates, along with consent-related requirements where applicable. These checks should be part of the communication process, not an afterthought.
Helo.ai's SMS product page covers bulk and transactional SMS, and its DLT management service supports registration and template mapping. TRAI lists the sender steps in its advice to senders.
3. WhatsApp: Best for Conversational and Rich Customer Alerts
WhatsApp is useful when an alert needs to do more than deliver information. It can give customers a way to respond, ask questions or take the next step within the same conversation.
Common use cases:
- Order and delivery updates with tracking links.
- Payment reminders with a payment action.
- Service appointment updates.
- Loan application status notifications.
- Customer support and follow-up conversations.
Businesses can use approved message formats, media and interactive elements to make updates easier to understand and act on.
There are messaging rules to consider. On the WhatsApp Business Platform, businesses can initiate conversations using approved message templates. When a customer messages a business, the 24-hour customer service window allows free-form replies during that period. Outside that window, approved templates are required.
Pricing change: Meta's documentation says it began charging per message for service messages, and for utility messages sent in response to users, from 1 October 2026. These are the replies sent inside the 24-hour customer service window. Check Meta's pricing update before you budget WhatsApp alerts.
WhatsApp is therefore a strong choice when the customer may need to respond or continue the interaction, rather than simply read an alert.
To explore WhatsApp for alerts with Helo.ai, see its WhatsApp product page.
4. RCS: Best for Rich, Branded and Interactive Messaging
RCS, or Rich Communication Services, brings richer messaging capabilities to supported messaging apps and devices. It can make a business alert feel more like an interactive experience than a plain text message.
Depending on device and network capabilities, RCS for Business can support:
- Branded sender experiences.
- Images and rich cards.
- Suggested replies and actions.
- Carousels and interactive elements.
- Links that take customers to relevant pages or services.
Common use cases:
- Retail promotions and product updates.
- Travel itinerary and booking information.
- Banking service updates with relevant actions.
- Delivery notifications with tracking options.
- Appointment reminders with confirmation actions.
RCS availability is not universal. Businesses should check whether a recipient's device and number are reachable through RCS and what features the device supports.
A fallback to SMS can help reach customers who cannot receive RCS. However, delivery receipts should be checked before sending the fallback. Otherwise, customers may receive the same alert twice.
How the check works: Google's RCS for Business documentation says a capability check returns a successful response only if the phone number has connected to RCS within the last 31 days, and a 404 means the user cannot be reached through RCS (capability checks). Before falling back to SMS, Google says to confirm the message was not delivered and to always check delivery receipts (best practices).
In India, Google also sets country-specific rules for RCS agents, including promotional traffic limits and the Multi-use type not being available (use-case rules). See Helo.ai's RCS page and its guide to RCS Business Messaging for e-commerce and retail.
Plan your alert channels with Helo.ai
Share your customer base, alert types and markets, and the Helo.ai team can help you map SMS, WhatsApp and RCS to each use case.
Which Channel Should You Choose for Different Alerts?
The best channel depends on what the customer needs to know or do. Use this table as a starting point.
OTP or login verification
RECOMMENDED CHANNELSMSWorks across a wide range of mobile devices without an app
Banking transaction alert
RECOMMENDED CHANNELSMS or app pushSMS offers broad reach; app push suits customers using the banking app
Order confirmation
RECOMMENDED CHANNELWhatsApp, SMS or RCSThe channel can be selected based on the information and actions required
Delivery tracking update
RECOMMENDED CHANNELWhatsApp or RCSSupports richer information and useful tracking actions
App-specific activity
RECOMMENDED CHANNELPush notificationTakes the user directly back to the relevant app experience
Payment reminder
RECOMMENDED CHANNELSMS or WhatsAppSMS delivers a concise reminder; WhatsApp can support a conversational follow-up
Service outage alert
RECOMMENDED CHANNELSMS, with other channels where appropriateUseful when the update needs broad reach and should not depend on app installation
Appointment confirmation
RECOMMENDED CHANNELWhatsApp, SMS or RCSThe right option depends on whether the customer needs to confirm or reschedule
These are starting points, not fixed rules. A bank may use app push for customers who actively use its app and SMS for customers who do not. A retailer may use RCS for a rich delivery update and SMS when RCS is unavailable.
Quick channel picker
If the cards above do not settle it, start from the customer's situation.
This picker is Helo.ai's summary of the points above, not a fixed rule.
What Should Businesses Consider Before Choosing a Channel?
Before deciding, look beyond the message format. Consider these five factors:
1. Customer access
Does the customer have your app installed? Are they subscribed to web push? Can their device receive RCS? If the answer is uncertain, a channel with broader reach may be more appropriate.
2. Urgency
For time-sensitive alerts, consider how quickly the message can reach the customer and what happens if the first channel is unavailable. A fallback strategy can help, provided delivery status is checked to prevent duplicate alerts.
3. Message complexity
A short OTP does not need a rich card or a conversation. A delivery update with tracking and support options may benefit from WhatsApp or RCS.
4. Customer action
If the customer needs to reply, confirm, reschedule or ask a question, choose a channel that supports that interaction. If the alert only needs to inform, a simpler channel may be enough.
5. Consent, permissions and compliance
Push notifications require device or browser-level permission. WhatsApp business messaging must follow Meta's policies. SMS communication in India must follow applicable TRAI requirements. RCS availability and features depend on device and network support.
The channel should fit both the customer experience and the rules governing the communication.
How an Omnichannel Approach Brings These Channels Together
Businesses do not have to choose one channel for every customer and every alert. Different customers may have different levels of access, preferences and engagement.
An omnichannel communication approach allows a business to use channels according to the situation. For example, an order update might be sent through WhatsApp, while SMS can be used when the preferred messaging route is unavailable. A banking app may handle app-specific activity through push notifications, while SMS supports customers who do not use the app.
A simple fallback sequence
The check-before-fallback step follows Google's RCS guidance and prevents duplicate alerts. Retries and timeouts need care too, because a timeout does not always mean a message was not delivered.
Helo.ai supports enterprise communication across SMS, WhatsApp, RCS, Voice and Email. These channels can help businesses manage different customer communication needs through an omnichannel approach.
Helo.ai's voice and email pages cover the other channels, and its guide to omnichannel customer engagement explains the wider approach.
Push notifications are a separate app or browser capability. Businesses that want to use app push need the relevant app infrastructure, permissions and notification setup; it should not be assumed to be a native Helo.ai messaging channel.
The objective is not to send every alert everywhere. It is to choose a channel that fits the customer, the message and the action required.
Talk to an expert
Talk to an expert to explore how an omnichannel communication strategy can support your customer alerts.
Customer alert channel checklist
Review each alert type against this list before you choose its channel.
- Does the customer have the app installed and notifications turned on?
- Do you need to reach customers who have no app or no data connection?
- Does the customer need to reply, confirm or reschedule?
- Have you confirmed opt-in or consent for each channel?
- Do you check RCS reachability before sending an RCS message?
- Is there a fallback channel, and does it wait for the delivery status?
- Are SMS templates, headers and links compliant with TRAI requirements?
- Do you track delivery, customer action and fallback use for each alert?
Frequently Asked Questions
What are push notifications?
Push notifications are messages sent by a mobile app or website to a user's device. They can appear on the lock screen, notification centre, desktop or browser, even when the app or website is not open.
What is the difference between app push and web push notifications?
App push notifications come from an installed mobile application. Web push notifications come from a website or web app through a supported browser. Both require the user to subscribe or grant the relevant notification permission.
Do push notifications require an internet connection?
Yes. App and web push notifications rely on internet connectivity and the relevant platform or browser notification services. SMS does not require mobile data, although it does require mobile network service.
What is a push notification badge?
A push notification badge is a small visual indicator, often a number or dot, displayed on an app icon to show new or unread activity. Its appearance depends on the operating system and app settings.
Is SMS better than push notifications?
Neither is universally better. SMS can reach customers without requiring an app or mobile data, while push notifications are useful for businesses with an installed app or subscribed web audience. The right choice depends on reach, urgency and the customer's access.
Can RCS messages fall back to SMS?
Yes. Businesses can use capability checks and delivery information to decide when an SMS fallback is needed. They should verify the RCS delivery status before sending the fallback to avoid duplicate messages.
Which channel is best for OTPs?
The draft comparison recommends SMS for OTPs and login verification because it works across a wide range of mobile devices without an app. Some apps also use push for in-app approvals, so choose by how your customers sign in.
Can WhatsApp send alerts without the customer messaging first?
Yes, using approved message templates, and the customer must have opted in. Meta's documentation says that outside the 24-hour customer service window you can send only pre-approved templates.
How do I check whether a customer can receive RCS?
Use a capability check through your RCS provider. Google's documentation says a successful response means the phone number has connected to RCS within the last 31 days and shows which features the device supports.
Conclusion
Push notifications, SMS, WhatsApp and RCS solve different communication needs. Push works well for app and web engagement. SMS offers broad mobile reach. WhatsApp supports conversations and customer actions. RCS adds richer, interactive messaging for supported devices.
The right choice is not about picking the newest channel. It is about understanding who needs the alert, how they can receive it and what they need to do next.
For many businesses, the strongest approach is to use channels together, with clear rules for selection and fallback, rather than relying on one channel for every customer.
Disclaimer. This article is general information, not legal, regulatory, compliance or technical advice. Platform rules, WhatsApp pricing, RCS rules and TRAI requirements change and vary by market, so check current requirements and consult qualified advisers. Helo.ai is the publisher and offers SMS, WhatsApp, RCS, voice and email products. Push notifications are an app or browser capability and are not described here as a Helo.ai channel. Sources were last checked in November 2026.
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