To manage the voicemail for your Teams phone, you can do the following:
- Open Teams and go to Settings by clicking on the three dots in the top right corner, then click on Settings.

- Click on the Calls tab in the settings menu.

- Scroll down to Manage voicemail. To record your own voicemail greeting, you can press Record a greeting. Note that you need a connected audio device with speakers and a microphone to record a greeting.

-
This will open a call tab where instructions for recording a greeting will be read. Use the numeric keypad to perform the action you want:
"To play and record your personal greeting, press 1.
To play and record your greeting for when you're away, press 2.
To exit, press the star (*) key."
If you do not record your own greeting, you will have a default greeting as your voicemail. - Under the same heading, Manage voicemail, you can also change the language for the default greeting, choose what happens when a call is redirected, as well as enter a custom greeting that will be configurated with text-to-speech.
Search the user manual