Choosing an SMS API
How To Choose The Best SMS API For Your Product.
There's no single "best" SMS API. There's the one that matches how you actually send messages. Here's what to weigh, and how the main options differ.
What actually matters
Four Questions To Ask Before Picking One.
Where does the number come from?
A rented virtual number, a dedicated short code, or a real SIM you already own. Each has different delivery behavior, carrier filtering risk, and cost structure.
How is it priced?
Per-message billing on top of a rented number adds up fast at real conversation volume. A flat plan against your own SIM's existing carrier cost can work out very differently depending on how many messages you actually send.
Can it receive replies, not just send?
A surprising number of "SMS API" products are send-only. If your workflow depends on customer replies (confirmations, support, opt-outs), confirm two-way messaging and webhook delivery before committing.
What happens when something fails?
Networks drop, phones go offline, carriers throttle. What matters is whether the API tells you the truth about delivery status, and whether a failed send queues and retries or just silently disappears.
Rented-number cloud APIs
The Big Names, And What They Actually Charge.
Per-message pricing changes often, so treat these as ballpark figures and confirm current rates directly before budgeting.
Twilio
2Plus ~$1.15/mo per rented number
3No monthly minimum, no included messages
4Largest ecosystem and docs
Plivo
1~$0.008 per SMS + carrier surcharges
2Plus ~$0.50/mo per rented number
3Plans from $25/mo, or pay-as-you-go
4Good fit for cost-sensitive bulk sending
Vonage
1~$0.008 outbound / ~$0.0065 inbound
2No monthly minimum
3Volume discounts need a sales conversation
4Best fit at high, bursty volume
Bird (MessageBird)
1From ~$0.003 per message, varies by number type
2Free tier: 5 messages/day
3Pro plan: $49/mo for 1,000 message credits
4Transparent pay-as-you-go pricing
Android-gateway options
The Closer Comparison: Other Phone-As-Gateway Services.
These use the same underlying idea as TexMax: a real Android phone sending over its own SIM, not a rented number. Worth knowing they exist.
SMS Gateway for Android
1Open-source, free to self-host
2Hosted plan: from $30/mo per device, unlimited SMS
3Free hosted plan capped at 50 messages total
TexMax
2€15/month, one paired device per account
3Hosted relay, queueing, and webhooks included
Where TexMax fits
One Request, Sent From A Real Phone.
Same shape of call you'd expect from any SMS API. The difference is what's on the other end of it.
# Send a message through a real, paired Android SIM
curl -X POST https://api.texmax.app/messages/send \
-H "Authorization: Bearer tmx_your_api_key" \
-H "Content-Type: application/json" \
-d '{
"deviceId": "8jr3ewqh55y7gyj3e0w0stw5",
"address": "+15551234567",
"body": "Your appointment is confirmed."
}'
curl -X POST https://api.texmax.app/messages/send \
-H "Authorization: Bearer tmx_your_api_key" \
-H "Content-Type: application/json" \
-d '{
"deviceId": "8jr3ewqh55y7gyj3e0w0stw5",
"address": "+15551234567",
"body": "Your appointment is confirmed."
}'
Questions worth answering upfront.
Is TexMax cheaper than Twilio?
TexMax is a flat €15 per month with no per-message fee, since sending rides your existing carrier plan. Twilio charges roughly $0.008 to $0.013 per message once carrier surcharges are added, plus a monthly fee for the rented number, so cost scales directly with volume. Below a few thousand messages a month, TexMax's flat rate is usually cheaper; at very high, bursty volume, a dedicated short code from a provider like Twilio is usually the better fit.
Are there other Android-phone SMS gateway services like TexMax?
Yes. textbee and SMS Gateway for Android are open-source projects built on the same idea, a real phone sending over its own SIM. Both can be self-hosted for free, or used as a hosted service starting around $10 to $30 a month depending on message volume and device count. TexMax is a hosted-only alternative at a flat €15 a month, one paired device per account, with the relay, queueing, and webhook delivery already built in.
Does TexMax support two-way messaging and webhooks?
Yes. Incoming replies are captured from the paired Android phone and delivered to your application through a webhook, the same pattern used by Twilio, Plivo, and Vonage.
Do I need a dedicated business SMS number to use TexMax?
No. TexMax sends through the SIM already in your paired Android phone. There's no separate virtual or rented number to provision.
What's the real difference between TexMax and a rented-number SMS API?
A rented-number provider leases you a virtual number and routes messages through their own carrier infrastructure, billing per message. TexMax routes messages through a physical Android phone's own SIM and mobile network, so the number is a real, ownable one and the underlying carrier cost is whatever your existing mobile plan already covers.
Your phone. Your SIM. One API.
See If TexMax Fits Your Use Case.
Pair a phone and send a real test message in minutes.