# SMS/MMS Regulations for USA

SMS and MMS marketing in the U.S. is **strictly regulated** by the **CTIA**, and senders must comply to avoid penalties or message blocks.

### Key Restrictions (for long numbers only)

**Message Format**

* Standard SMS length: **160 characters** per message.
* Unicode messages are limited to **70 characters** per message.
* The **Euro (€) symbol, binary encoding, and concatenation** are not supported.

**Sender ID**

* Only **long numbers or short codes** can be used—**alphanumeric sender IDs are not allowed**.
* The sender's **FROM address** must use a **pre-approved U.S. sender number** in international format.

**Message Content**

* Messages must **not contain offensive, inflammatory, or harmful content**.
* If targeting minors, the content must be **appropriate for all ages**.
* **Excessive use of keywords and URLs** can trigger spam filters, leading to message blocks.

**Opt-in & Opt-out Requirements**

* **Opt-in consent is required** before sending any SMS/MMS marketing messages.
* Every marketing message **must include an opt-out option**.
* Senders must use **two-way numbers**, allowing recipients to unsubscribe at any time.

**Message Frequency & Volume Limits**

* **High-frequency senders** should purchase additional numbers.
* **Carriers may reject messages** if more than **one message per second** is sent from a single number.
* **Daily limit for long numbers**: **5,000 messages**—exceeding this may lead to number blocking.
* **For two-way SMS/MMS numbers**, carriers expect **balanced inbound and outbound traffic**.

Following these regulations ensures compliance and prevents disruptions in SMS marketing campaigns.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.satisfilabs.com/resource-center/marketing-engine/campaigns/messaging-campaigns/sms-regulations/sms-mms-regulations-for-usa.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.