Change the default language for greetings and emails
If you are a global administrator, you can set up Skype for Business to play its default voicemail greeting in another language. The default system greeting is something like, "Please leave a message for John Smith. After the tone, please record your message. When you finish recording, hang up, or press the pound key for more options."
First, read this important info:
The languages that are available to you are determined by the location of your organization. For example, if your organization is located in the United States, you can set the default language to English or Spanish. If your organization is located in Canada, you can choose between English and French. For a list of supported languages in Teams and Skype for Business, see the following:
Changing languages for individual user's voicemail greeting and voicemail messages. You can change the preferred language for users, which will change the language of their voicemail greeting and voicemail messages sent to their Outlook mailbox. For more information, see How to set language and region settings for Microsoft 365 or Office 365.
Users can change their own greeting language through their settings after they sign in. For more information, see Change your display language and time zone in Microsoft 365 for Business
Do you want to record your outgoing voicemail message? See Check Skype for Business voicemail and options. For Microsoft Teams - Users can change their voicemail settings from the Teams desktop client settings
Do you want to change the voicemail prompt language? For Skype for Business - https://mysettings.lync.com/voicemail and choose a new language under Prompt Language. For Microsoft Teams - Users can change their voicemail greeting from the Teams desktop client settings
Change the system language for everyone in your organization
In the Microsoft 365 admin center, choose Settings > Settings > Organization profile.
Select a language from the Preferred language list for everyone in your organization.