Guide · 6 min read

Most SMS services charge for every message. But there’s a perfectly good SMS sender sitting in a drawer: an old Android phone with a SIM card. With the right software it becomes a gateway that WordPress can use to send and receive texts — billed through the mobile plan you already pay for.

What you need

• A WordPress site (5.6+, PHP 7.4+, HTTPS recommended)
• An Android phone running Android 8.0 or newer, with a SIM that can send texts
• The SwarmSMS plugin and Android app
• A power source and a stable connection for the phone (Wi-Fi or mobile data)

Step 1: Install the plugin

Download the plugin zip from your account, then go to Plugins → Add New → Upload Plugin and activate it. A SwarmSMS menu appears. Open License, paste your key and activate. Then set your default country code in Settings (for example 61 for Australia) so numbers like 0400 111 222 are understood.

Step 2: Install the app on the phone

Open SwarmSMS → APK. Scan the QR code with the phone, download the file and allow Install unknown apps when Android asks. Open the app and allow the SMS and notification permissions.

Step 3: Pair the phone

In WordPress open SwarmSMS → Devices and click Generate pairing code. In the app, tap Scan QR code. The phone shows Gateway enabled and appears online in your Devices list. The pairing code is single-use and expires in ten minutes.

Step 4: Keep it alive

Phones love to sleep. Tap Allow background activity in the app and set its battery mode to Unrestricted (on Samsung: Settings → Apps → SwarmSMS → Battery). Leave the phone on a charger. SwarmSMS can email or text you if it goes offline or the battery runs low.

Step 5: Send a test

Go to SwarmSMS → Send, enter your own number and a message, and press Send. The status moves from pending to dispatched, sent and delivered. Replies appear in Conversations.

Make it faster and more reliable

• Instant delivery: add free Firebase push so messages go out in about a second.
• More phones: pair a second phone; if one goes offline, messages move to the other.
• A real cron job: call wp-cron.php every minute for dependable campaigns and alerts.

A note on costs and carriers

There are no message fees from SwarmSMS, but your carrier’s rules still apply. Many plans include unlimited texts with fair-use limits, so use message gaps and daily limits, and only text people who have agreed to hear from you.