Is there a way for employees to access their voicemail messages from an outside phone?
Voicemail is a server side feature, below three methods should support by your PBX server.
1. If the outside phone can register to the same PBX server of the voicemail account which you want to listen to, you can dial the voicemail access code and password to access the phone’s voicemail. Take 3CX PBX for instance, supposed the voicemail access code is *4, extension is 100, you can dial from the outside phone with *4, do not enter any digit when phone prompts to enter the PIN#, after about 10 seconds, it will prompt you to enter the extension and PIN#, then enter 100 and PIN# to get the voicemail message.
Note: It differs from different PBX server.
2. Login your PBX server webpage with your extension; manage the voicemail in this webpage.
3. PBX server has an application provided for user and user can access the voicemail through this application.