Bulk SMS: The Setup and Send Guide
Send thousands of texts from your own number, at zero per-message cost, without a gateway contract.
Bulk SMS still gets opened. No spam folder, no feed algorithm burying it — just a text that lands on the lock screen within seconds. But shop for a provider and you immediately hit monthly plans, per-block pricing, and minimum commitments for something that should be simple: send a message to a list, get it delivered.
Bulk SMS through WaSMS works differently. You install a small gateway app on an Android phone, pair it with your WaSMS account, and every message goes out through that phone's own SIM — using its normal SMS allowance, the same as if you typed the text yourself. No message-block pricing, no separate SMS vendor account.
Bulk SMS on Your Own SIM
The gateway app runs quietly in the background on any Android phone (an old one you're not using works fine). WaSMS queues the messages, sends them to the app over a secure connection, and the app hands them to the phone's SMS radio one at a time.
This is the same setup covered step by step in setting up your Android SMS gateway — if you haven't paired a phone yet, do that first. Everything below assumes a connected gateway.
Because you're sending through a real SIM, your bulk SMS behaves like normal texting to carriers — which is exactly what keeps it out of spam filtering built for dedicated short codes.
Building a Clean List
Bulk SMS lives or dies on list quality. A list of numbers scraped from old invoices or a spreadsheet nobody's touched in two years will bounce, and repeated bounces are what get a SIM flagged.
Before your first send:
- Dedupe. One number appearing twice sends twice and looks like a glitch to the recipient.
- Normalize format. Numbers need a consistent country code format — WaSMS will reject malformed entries at import rather than let them fail silently mid-send.
- Segment by consent. Only import numbers that opted in somewhere — a checkout form, a sign-up sheet, a reply to a previous text. This matters more than volume.
Dr. Chen's clinic learned this the slow way: an old list from a front-desk sign-in sheet had 15% dead numbers, and the first bulk send got flagged as suspicious by one carrier within an hour. Re-importing a list built from the clinic's own appointment-confirmation opt-ins fixed delivery rates completely on the next send.
Sending Your First Campaign
From the WaSMS dashboard, bulk sends live under Campaigns → New SMS Campaign. Upload a CSV, map the phone number column, write your message, and preview it before sending.
If you're sending programmatically instead of through the dashboard:
curl -X POST https://api.wasms.net/v1/sms/bulk \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"channel_id": "gw_8841",
"recipients": ["+14155550100", "+442071234567"],
"message": "Hi {{first_name}}, your order ships tomorrow. Track: {{link}}"
}'
Use merge fields like {{first_name}} so the message doesn't read like a blast. A campaign guide for planning the offer and copy around this send lives in the SMS campaign guide.
Rate-Limit Safety
This is the part most guides skip, and it's the part that actually determines whether your number survives past the first campaign. Carriers watch for a SIM that suddenly sends hundreds of identical messages in a burst — that pattern looks like spam regardless of content.
WaSMS paces sends automatically per gateway, but you can help it:
- Split large lists across sends over a few hours instead of one blast
- Vary merge-field content instead of sending identical text to everyone
- Watch for a spike in failed sends mid-campaign — that's the earliest sign of throttling, not the failure itself
The same caution applies on the WhatsApp side of WaSMS — the SIM blocked troubleshooting guide covers what to do if a number does get flagged and how to recover it.
Delivery Reports
After a send, WaSMS shows per-message status: queued, sent, delivered, failed. Delivered means the carrier confirmed the handset received it — not that it was read, since SMS has no read receipt.
If a chunk of a campaign shows failed rather than delivered, don't resend blindly. Check the delivery reports troubleshooting guide first — a batch of failures usually traces to one bad number format or one carrier-side block, not a broken gateway.