SMS Gateways: How They Work and Self-Hosted Options
SMS gateways route texts between apps and phones. Learn the cost difference between carrier APIs and a self-hosted Android gateway plus the exact numbers that matter for real campaigns.
TL;DR
SMS gateways connect software to mobile networks. Traditional services charge $0.0075 to $0.05 per text. FlixySMS instead uses your existing Android phone and carrier plan so the per-message cost drops to whatever your monthly plan already includes. A single handset sends 30-100 messages per minute and multi-device setups scale beyond that. Integrations with Shopify, WooCommerce, and Google Sheets let events trigger messages without manual work.
An SMS gateway routes messages between software and mobile networks. Traditional providers act as middlemen that bill per text while self-hosted setups use hardware you already own.
Traditional SMS Gateway Costs
Carrier-based APIs from companies such as Twilio charge between $0.0075 and $0.05 per message. A campaign of 10,000 texts therefore costs $75 to $500 before any delivery failures. Volume discounts exist but the per-message model stays intact.
Self-hosted gateways avoid that line item. Your carrier plan already includes the texts so the only recurring expense is the platform subscription itself.
How an Android Phone Becomes the Gateway
FlixySMS installs on a standard Android handset and turns it into the sending hardware. The phone connects to the mobile network exactly as it does for personal use. Outbound messages leave through the same SIM and tower path.
A single device handles 30 to 100 SMS per minute depending on the carrier's throttling rules. When volume exceeds that range, users add a second phone and the software distributes the load across both SIMs.
Messages longer than 160 characters are split automatically. Each segment receives the required concatenation headers so the recipient's phone reassembles the full text.
See the step-by-step process on our How it Works page.
Hardware and Carrier Requirements
Any recent Android phone with a working SIM works. Dual-SIM models let one device carry two numbers. Keep the handset plugged in and connected to Wi-Fi for stable operation during long campaigns.
Business Features Built on the Gateway
Bulk campaigns accept contact lists imported from Google Sheets. The same sheet can update delivery status after each send.
Auto-responders trigger on keywords such as STOP or HELP. A configured reply goes out within seconds and keeps the conversation compliant.
Scheduled sends queue messages for later delivery. The queue survives restarts and network hiccups.
Delivery tracking records the exact timestamp when the carrier accepts each text. Failed sends are logged with the carrier error code for later review.
Two-way conversations appear in a single thread view. Replies from customers land in the same dashboard used for outbound sends.
API Access for Programmatic Sends
The REST API accepts JSON payloads for single or batch messages. A minimal request looks like this:
{
"to": "+15551234567",
"message": "Order #48291 has shipped.",
"from": "MyStore"
}
Authentication uses an API key generated inside the dashboard. Rate limits match the combined throughput of the attached phones.
Full endpoint reference is available in the API Documentation.
Integrations That Trigger Messages
Shopify can send order confirmations the moment a purchase completes. Abandoned-cart reminders go out 30 minutes after a visitor leaves the checkout page.
WooCommerce fires similar events for new orders, refunds, and low-stock alerts.
Custom webhooks let any platform post a payload that the gateway then converts into an SMS. Google Sheets serves as a simple CRM when the sheet contains phone numbers and message templates.
Details for each integration appear on the FAQ page.
Pricing and Quotas
Plans scale from a free tier for testing up to enterprise contracts. Each paid plan lists a monthly SMS quota that resets on the billing date. Over-quota sends pause until the next cycle or an upgrade.
Current limits and add-on options are listed on the Pricing page.
Getting Started
Create an account at the Dashboard signup screen. Install the Android app on one or more phones, grant SMS permissions, and connect the devices to your account. From there you can import contacts, set up an auto-responder, or send your first campaign directly from the web interface.
The setup takes under ten minutes on a typical phone and does not require carrier approvals beyond the SIM you already use.
Frequently Asked Questions
How does an SMS gateway work?+
An SMS gateway receives a message from software and forwards it to a mobile network. Traditional gateways use carrier connections while FlixySMS uses the SIM card inside an Android phone you control.
What is the cost of self-hosted SMS versus Twilio?+
Twilio charges $0.0075 to $0.05 per message. FlixySMS uses the texts already included in your phone plan so the only added cost is the monthly platform subscription.
How many SMS can one Android phone send per minute?+
A typical handset sends 30 to 100 SMS per minute before the carrier applies throttling. Adding more phones increases total throughput in parallel.
Does FlixySMS support messages longer than 160 characters?+
Yes. The software splits long texts into segments and adds the headers needed for automatic reassembly on the recipient's phone.
Which platforms integrate with FlixySMS for order alerts?+
Shopify and WooCommerce can send order confirmations and abandoned-cart messages. Google Sheets supplies contact lists and custom webhooks work with any other system.