A group voicemail account is almost exactly the same as a standard Skype for Business account.
1) Please login to the portal and select "Voicemail" and click "Create".
Please ensure BOTH addresses entered (they can be the same) are VALID email addresses.
We recommend using a distribution group within your email system (usually free of charge) as the voicemail SIP address.
For example, set firstname.lastname@example.org as a distribution group with the support desk users as members.
Please ensure this distribution group is enabled BEFORE creating the group voicemail.
2) You'll then receive a welcome email to the email address you entered above. Set the password as you would a standard account.
3) Sign into a Skype for Business client using this new account, press and hold "1" on the keypad and follow the instructions.