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> Learn about the modes of SMS operation and use cases available on your emnify account for IoT devices

Short Message Service (SMS) uses the same basic technology on IoT devices as that employed with consumer mobile devices.
However, in the context of IoT devices, there are more modes of SMS operation and use cases that provide additional capabilities.

## Classifications

### SMS P2P

Peer-to-peer (P2P) SMS describes the mode of sending SMS from one device to another.

For IoT devices, this poses a security threat.
Anyone with the correct MSISDN can issue commands to the device since there isn't any built-in authentication process.

P2P also isn't suitable for IoT device use cases in which a device needs to update, interact, or transmit frequently because a device is limited to receiving only six SMS messages per minute in this mode.

### SMS A2P

SMS application-to-peer (A2P) describes the mode of SMS data exchange between a device and an application.
One example of this is sending SMS using the emnify Portal.

Unlike P2P, A2P lets you interact with *multiple* devices using an application.
Because A2P SMS can be automated, you can interact with your devices at scale.
It also tracks messages, which enables you to see when a message has been delivered.

### SMS MO and MT

Because the costs of sending SMS from an IoT device are higher than the cost of receiving SMS, all SMS usage is logged as either [SMS MO](https://www.emnify.com/iot-glossary#sms-mo) (sent) or [SMS MT](https://www.emnify.com/iot-glossary#sms-mt) (received).

Using the emnify REST API, you can dispatch SMS MO from devices as HTTP `POST` requests toward a user-configurable URL.

To activate or deactivate SMS MO or MT for a group of devices, you can use the toggle switches in a new or existing **Service Policy** to which the devices are assigned.
See [Service Policies](/portal/device-policies#service-policies) for more details.

## Open the SMS console

Each device has an SMS console.
To open a device's SMS console, select its message icon.

#### From Connected Devices

![Message icon in a device row of the Connected Devices list](/_fern-img/d44e223e35fc213bbc25a50dbbc0c75771de036669423224ae659fdb145dc3c6.webp)

#### From Device Details

![Message icon next to the device name in device details](/_fern-img/850784c78bdb16129e6e10b1af6b73c66b643d6ab2d12272d7c243160dfb4a72.webp)

#### Show the Device SMS console

![SMS console with a message waiting for delivery, a message text field, and a Source field](/_fern-img/2f41b0e90be402d84cef90c96b292bd8e3c70de14b4613fdd015a9c42f5d0b88.webp)

## Available guides

* [Send SMS via the emnify Portal](/portal/how-tos/send-sms-portal)
* [SMS operations using the emnify REST API](/developers/connectivity/sms-operations)
* [Set up a Zapier SMS integration](/portal/how-tos/zapier-sms-integration)
* [Configure Webhook or SMPP as your SMS interface](/portal/how-tos/configure-sms-interface)