Voicemail
To change the messages (welcome) of your voicemail, you must do so through your phone:* 97 (and press dial) asks for your password (the same as the extension if you have not changed it)
0 (zero to set)
1 (Message from not available)
2 (Message from busy)
3
4 Temporary message (it's the one that comes out by default)
5 Change the password of the voicemail
Option 4 is the one you have to record.
You have other options regarding your extension, at the following address: http: //centraleta.icmab.es/recordings and in the settings section you can change the password of the mailbox (if I have not changed it, it is the same what the extension)