1. What is an SMS MT?

There are two kinds of SMS:

• Mobile Originated (MO) SMS when a device sends a message
• Mobile Terminated (MT) SMS when a device receives a message

In the EUI, they will appear differently and will also be charged differently. This is a reason why you can enable or disable SMS MO or MT for your endpoints in the basic configuration of your "Service Profile".

Not all SMS MT will appear in the EUI as our SMS Center (SMSC) does not handle messages sent by devices using other providers (Vodafone or Deutsche Telecom for example). This is the difference between A2P and P2P SMS

2. A2P vs P2P SMS

• A2P stands for Application to Person. One-way SMS to which recipients are not expected to reply. A2P messaging includes but is not limited to marketing messages, appointment reminders, notifications and pin codes.�A2P SMS MT, always go through our SMSC and are therefore registered in the EUI.
• P2P stands for Person to Person: two way messaging like when you use your phone to send a text message to a friend. �P2P SMS MT go through an SMSC that EMnify does not control. We therefore cannot know if a message has been received and cannot display any information in the EUI.

Via the EUI, under "service profile->basic configuration->SMS" you can also choose to enable or disable P2P or A2P SMS.

To update some devices, like GPS trackers eg, an Over The Air (OTA) update is sometimes necessary. Those happen via SMS and will be considered as A2P SMS MT ie handled by EMnify's SMSC and displayed in the EUI. Such devices are not always connected to the network though, they sometimes only connect once a day. For such devices, we implemented the SMS Buffering.�

3. SMS MT Buffering

In normal cases, our SMSC will try to periodically deliver SMS MT to endpoints. Besides those attempts, our SMSC will also be notified by the visited network, when a device is ready to receive a SMS. At this point, the EMnify SMS center will try to send the message again directly. Thanks to this "Buffered SMS-MT" tool, our SMSC can deliver messages to connected devices at the right time. Note that our SMSC will only buffer SMS 24 hours.

For the SMS MT Buffering function to work, you need to enable two functions in the service profile:

1. SMS MT
2. A2P SMS

In the EUI, under "endpoint->select an endpoint-> SMS", you can see the SMS MT received by your device. When an SMS if buffered, it will appear yellow as bellow.