VAS & Two-Way SMS

Value-Added Services covers everything that happens on a shortcode: subscribers text in, you reply, and they subscribe to premium content products that bill on a recurring cycle.

VAS is mostly inbound

This is the one integration where we call you more than you call us.

The important half is the webhook you expose. Almost every flow starts with a subscriber texting your shortcode, which arrives as an HTTP POST to your server. If your webhook is down, your service is down — no amount of correct outbound code compensates.

Build the receiver first.

How it differs from A2P SMS

They’re different products with different pipelines, and it’s worth being precise about which one you’re using:

	A2P SMS	VAS / Two-Way
Direction	You → subscriber	Subscriber → you → subscriber
Sender	Your brand name (9bits)	Your shortcode (48974)
Can they reply?	No	Yes — that’s the point
Endpoint	/ng/v1/sendsms	/vas/ng/v1/service/two-way/sendsms
Body format	JSON	form-encoded
Message field	content	text
Billing	You pay per message	Subscriber pays; you get revenue share

These two APIs are not interchangeable

A2P SMS takes JSON with a content field. Two-way takes form-encoded input with a text field.

They are different services with different pipelines, and copying a payload from one to the other will fail. See Receiving messages for the exact shape.

The flow

A typical subscription

1. Subscriber texts games28 to your shortcode 48974.
2. We POST that to your webhook with a session_id.
3. You reply via POST /vas/ng/v1/service/two-way/sendsms, echoing the session_id.
4. The operator bills them and we POST you an activation_notification.
5. Every cycle, we POST a renewal_notification — this is your revenue event.
6. When they stop, we POST a deactivation_notification. Revoke access.

Sessions

Inbound messages carry a session_id. Echo it back on your reply and we thread the exchange as one conversation — which is what makes multi-step flows (menus, quizzes, confirmations) work.

Start here

Receiving messages The inbound webhook, keyword routing, and how to reply.

Subscription lifecycle Activation, renewal and deactivation events — and reconciling revenue.

Try it live Run the reply endpoint against your account.