Use push notifications first, then SMS for the users who still ignore you. That is the cleanest answer for most apps. Push is cheap, fast, and perfect for daily nudges. SMS is louder, pricier, and better for moments that matter. Also, people still like texts from brands more than you might expect: SimpleTexting reported that 71% of consumers subscribed to receive texts from businesses in 2024 [source: SimpleTexting].
TLDR: For customer re-engagement, push notifications are your everyday tool, while SMS is your rescue flare. If a food app has 10,000 sleepy users, a push campaign might bring back 600 users at almost no message cost, while SMS might bring back 1,200 but cost real money. Firebase is great if your team wants control and already uses Google tools. OneSignal is easier if your marketing team wants segments, journeys, and reports without bothering developers every five minutes.
SMS vs push notifications: the simple version
Push notifications are messages that pop up from your app. They need the app installed. They also need permission from the user. No permission, no push. Sad little silence.
SMS messages are text messages. They do not need your app to be open. They do not even need your app to be installed. They only need a phone number and legal consent. That makes SMS powerful. It also makes it risky if you abuse it.
Think of it like this:
- Push: “Hey, your cart is waiting.”
- SMS: “Your order arrives in 5 minutes.”
- Push: cheap poke.
- SMS: loud knock on the door.
When push wins
Push wins when you need many small touches. It is great for app habits. It is great for reminders. It is great for “come back and finish this thing” moments.
Use push for:
- Cart reminders.
- New content alerts.
- Daily streak reminders.
- Flash sales.
- Game rewards.
- Subscription usage nudges.
Push is also cheap. With Firebase Cloud Messaging, sending push messages is free. Of course, “free” never means “zero work.” Someone still has to set up tokens, topics, permissions, retries, events, and all the other tiny gremlins that hide in app messaging.
The annoying bit? Push can vanish. Users turn it off. Phones group it. Focus modes hide it. The app may be uninstalled. Honestly, it feels like shouting through a pillow when your opt-in rate is low.
When SMS wins
SMS wins when the message is urgent, personal, or tied to money.
Use SMS for:
- Passwordless login codes.
- Delivery updates.
- Appointment reminders.
- Payment alerts.
- High-value cart recovery.
- Win-back offers for VIP users.
SMS cuts through noise. People check texts. Phones display them clearly. Even users who deleted your app may still get the message.
But SMS costs money. It also has rules. You need consent. You need opt-out text like “Reply STOP to unsubscribe.” You need to avoid spammy behavior. One lazy campaign can annoy thousands of users in under a minute. That is not growth. That is a tiny PR fire.
Firebase for re-engagement
Firebase is the developer-friendly option. Its push engine is Firebase Cloud Messaging, often called FCM. It works for Android, iOS, and web push.
Firebase is strong if your team wants to build custom flows. It connects nicely with Firebase Analytics, Remote Config, A/B Testing, and Crashlytics. If your app is already built around Firebase, this can feel natural.
Firebase is best for:
- Apps with strong developer support.
- Teams that want full control.
- Product-led growth tests.
- Custom triggers from app events.
- Low-cost push at scale.
Example: A fitness app can send a push when a user misses two workouts. If the user opens the app, great. If not, the app can change their home screen offer using Remote Config. That is neat. Very nerdy. Very useful.
The rough part is the marketing workflow. Firebase can do a lot, but it is not always cozy for non-technical users. Expect to waste time on setup if your marketer wants “just a quick campaign” with five branches, three audiences, and a coupon rule that changes on Tuesdays.
OneSignal for re-engagement
OneSignal is built more like a messaging control room. It supports push, in-app messages, email, and SMS, depending on your plan and setup. It is popular because marketers can create campaigns without asking engineering for every tiny change.
OneSignal is best for:
- Marketing teams that move fast.
- Apps that need push plus SMS.
- Simple audience segments.
- Automated re-engagement journeys.
- Clearer campaign reporting.
OneSignal makes it easier to build a journey. For example:
- User adds shoes to cart.
- After 2 hours, send push.
- If no open, wait 24 hours.
- Send SMS with a 10% discount.
- If purchase happens, stop the sequence.
That kind of flow is the sweet spot. Push does the cheap work first. SMS steps in only when the user keeps ghosting you.
Which one should you choose?
Choose Firebase if your app team wants control and your budget is tight. It is also a smart pick if push is your main channel. You can build a strong system with it. You just need developer time.
Choose OneSignal if speed matters more than custom code. It is better for teams that need campaign tools now. It is also better when SMS and push need to work together in one place.
Here is the quick cheat sheet:
- Lowest push cost: Firebase.
- Easiest marketer workflow: OneSignal.
- Best for custom app logic: Firebase.
- Best for multi-channel journeys: OneSignal.
- Best for urgent messages: SMS.
- Best for frequent reminders: Push.
A simple customer re-engagement plan
Do not start with a giant campaign monster. Start small. Pick one user group. Pick one action you want back.
For example, take users who installed your app but did not open it for 14 days. Send a push first:
“Still thinking it over? Your saved items are waiting.”
If they ignore it, wait 24 hours. Then send a second push with a stronger reason:
“Last chance: get 15% off your saved cart today.”
If they are high-value users and gave SMS consent, send one text:
“Your cart is still saved. Use SAVE15 today. Reply STOP to opt out.”
Now measure it. Track opens, clicks, purchases, opt-outs, and uninstalls. If SMS brings more sales but also many opt-outs, slow down. People are not piñatas. Stop whacking them with coupons.
Image not found in postmetaWhat to measure
Do not obsess over open rate alone. It can lie. A message can be opened and still do nothing.
Watch these numbers:
- Reactivation rate: how many dormant users returned.
- Conversion rate: how many completed the target action.
- Revenue per message: money made per send.
- Opt-out rate: how many users said goodbye.
- Uninstall rate: the silent scream of bad messaging.
A healthy campaign might reactivate 5% to 12% of dormant users, depending on your app and offer. SMS may beat push on response. Push usually wins on cost. The best setup often uses both.
The final pick
If you are early, use Firebase plus push. It is cheap and strong. If you have traffic, a marketing team, and a need for SMS, use OneSignal. It keeps campaigns simpler.
The real magic is not the tool. It is restraint. Send useful messages. Respect timing. Save SMS for moments that deserve it. Your users will come back more often when your app sounds helpful, not needy.