For you handsets and MDTs to work you will need to create Terminals within Dispatch (sometimes referred to as User or Handsets) and have them assigned channels. Channels can be set up here.

Adding a New Terminal

Click on the Terminals icon in the left navigation bar (looks like a hand held radio) to access the terminal settings. Once there, find the Terminals and select the "+" sign to show the ‘Add Terminal’ modal.

Clicking the '+' icon shows the following modal.

Please note that the "Telephone number" is not required. It is only supported on some handsets and with particular SIMs.

Just like channels terminals need a unique name in order for the sharing between organisations to work. Here you can see the created user jc8899:

This username must be 10 characters or fewer long and can only contain letters and numbers.

For help on how to sign users into their handsets, please read the Setting up a Handset help article  but before you do that make sure you assign some channels to the user