Voice message services
Microsoft Exchange Online offers hosted voice mail services, which provide:
Call answering (voice mail)
Dial-in user interface to Exchange (Outlook Voice Access)
Dial-in interface for callers (auto attendant)
Hosted voice messaging services allow a company to connect its on-premises phone system to voice mail services provided by Exchange Online. Voice mail messages are recorded and stored in the Exchange Online infrastructure, allowing users to access their voice messages from Outlook, Outlook on the web, or mobile phones. All telephony connections to Exchange Online require voice-over-IP (VoIP) protocols. Administrators can connect on-premises IP PBXs or PBX phone systems using VoIP media gateways and session border controllers (SBCs) to Exchange Online. A VoIP media gateway is not required if the customer has deployed an IP PBX or if a PBX supports VoIP directly and is interoperable with Exchange voice messaging services. SBCs are deployed in the perimeter of the customer network to connect an on-premises telephony network and help secure the communications (and the customer network) against eavesdropping and intrusion. Interoperability with the voice capabilities of Microsoft Lync Server 2010 and 2013 is also supported.
The voice messaging services features available in Exchange Online are similar to those offered in on-premises Exchange Server 2016. These include:
Play on phone from Outlook and Outlook on the web.
Missed call notifications.
Caller ID (using information in the Global Address List, users' personal contacts, custom Contacts folder, and contacts from external social networks).
Voice mail PIN reset from Outlook on the web and Outlook (see Reset a Voice Mail PIN).
Message Waiting Indicator (see MWI in Exchange Online for details).
Call answering rules (see Allow voice mail users to forward calls for details).
Protected voice mail in Exchange Online (see Protect voice mail in Exchange Online for details).
Voice mail preview (see Allow users to see a voice mail transcript for a list of supported languages).
Speech access to email, voice mail, calendar, personal contacts, and personal contact groups.
Directory search through Outlook Voice Access or an auto attendant.
Administrators configure and manage voice messaging services interoperability by using the Exchange admin center (EAC).
For more information about voice mail features, see Voice mail in Exchange Online.
The Automatic Speech Recognition (ASR) feature isn't available in menu navigation or directory search for Outlook Voice Access users or auto attendant callers using voice commands.
The customer must provide a telephony connection from the public switched telephone network (PSTN) using a VoIP gateway and PBX, IP PBX, or Skype for Business Server 2015.
The customer must provide the on-premises SBC hardware devices and ensure that the SBCs are correctly configured to connect to the online voice mail services. This includes configuring the appropriate level of security by using certificates and public and private IP interfaces and by enabling the correct TCP ports through their on-premises firewalls.
Hosted voice mail is available only to Exchange Online Plan 2 and Office 365 Enterprise E3 subscribers.
Third-party voice mail interoperability
On-premises voice mail solutions from third-party providers can interoperate with Exchange Online if they can forward voice messages through SMTP or if they support Microsoft Exchange Web Services. If the voice mail system does not natively support forwarding voice messages through SMTP, an email server can be kept on-premises to receive messages from the voice mail system and then forward them to the cloud using SMTP. Because many third-party voice mail systems use MAPI/CDO to interoperate with Exchange Server for advanced UM features, the full capabilities of these systems may not be available when SMTP is used for interoperability with Exchange Online.
Exchange Online UM support for third-party PBX systems via direct connections from customer operated SBCs will end in July 2018. Please see Discontinuation of support for Session Border Controllers in Exchange Online Unified Messaging for more information.
Skype for Business integration
Organizations can purchase Skype for Business Online as a standalone service or as part of Microsoft Office 365. Skype for Business 2015 on-premises is also supported. To learn more about Skype for Business Online, see Skype for Business Online service description.
To view feature availability across Office 365 plans, standalone options, and on-premises solutions, see Exchange Online service description.