Understanding Protocols, Ports, and Services in Unified Messaging

Understanding Protocols, Ports, and...

Applies to: Exchange Server 2007 SP1, Exchange Server 2007 Topic Last Modified: 2008-04-23

Microsoft Exchange Server 2007 Unified Messaging (UM) requires that several Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) ports be used to establish communication between Exchange 2007 servers and other devices. By allowing access through these IP ports, you enable Unified Messaging to function correctly. This topic discusses the TCP and UDP ports that are used in Exchange 2007 Unified Messaging.

UM Protocols and Services

Exchange 2007 Unified Messaging features and services rely on static and dynamic TCP and UDP ports to ensure correct operation of the computer that is running the Unified Messaging server role.

Session Initiation Protocol

Session Initiation Protocol (SIP) is a protocol that is used for initiating, modifying, and ending an interactive user session that involves multimedia elements such as video, voice, instant messaging, online games, and virtual reality. It is one of the leading signaling protocols for Voice over IP (VoIP), together with H.323. Most VoIP standards-based solutions use either H.323 or SIP. However, several proprietary designs and protocols also exist. The VoIP protocols typically support features such as call waiting, conference calling, and call transfer.

SIP clients such as IP gateways and IP Private Branch eXchanges (PBXs) can use TCP and UDP port 5060 to connect to SIP servers. SIP is used only for setting up and tearing down voice or video calls. All voice and video communications occur over Realtime Transport Protocol (RTP).

Real-time Transport Protocol

RTP defines a standard packet format for delivering audio and video over a given network, such as the Internet. RTP carries only voice/video data over the network. Call setup and tear-down are generally performed by the SIP protocol.

RTP does not require a standard or static TCP or UDP port to communicate with. RTP communications occur on an even UDP port, and the next higher odd port is used for TCP communications. Although there are no standard port range assignments, RTP is generally configured to use ports 16384 through 32767. It is difficult for RTP to traverse firewalls because it uses a dynamic port range.

T.38

T.38 is a faxing standard and protocol that enables faxing over an IP-based network. The IP-based network then uses Simple Mail Transfer Protocol (SMTP) and MIME to send the message to a recipient's mailbox. T.38 allows for IP fax transmissions for IP-enabled fax devices and fax gateways. The devices can include IP network-based hosts such as client computers and printers. In Exchange 2007 Unified Messaging, the fax images are separate documents encoded as Tagged Image File Format (TIFF) images and attached to an e-mail message. Both the e-mail message and the TIFF attachment are sent to the recipient's Exchange 2007 UM-enabled mailbox.

UM Web Services

The Unified Messaging Web services that are installed on a Client Access server use IP for network communication between a client, the Unified Messaging server, the Client Access server, and computers that are running other Exchange 2007 server roles. There are several Exchange 2007 Outlook Web Access and Microsoft Office Outlook 2007 client features that rely on UM Web Services to operate correctly.

The following Unified Messaging client features rely on UM Web Services:

The voice mail options that are available with Exchange 2007 Outlook Web Access, including the Play on Phone feature and the ability to reset a PIN.
The Play on Phone feature found in the Outlook 2007 client.

Note:
When an organization uses the Play on Phone and other client features in Exchange 2007 Unified Messaging, a computer that is running the Client Access, Hub Transport, and Mailbox server roles within the same Active Directory site is required in addition to the computer or computers that have the Unified Messaging server role installed.

Port Assignments

The following table shows the IP ports that Unified Messaging uses for each protocol and whether the IP ports that are used for each protocol can be changed.

IP Ports that are used for Unified Messaging protocols

Protocol	TCP Port	UDP Port	Can ports be changed?
SIP (Microsoft Exchange 2007 Unified Messaging Service)	5060 (TCP) 5061 (MTLS)		Ports are hard-coded and cannot be changed.
SIP (UM worker process)	5065 and 5066		Ports are hard-coded and cannot be changed.
RTP		Ports between 1024 and 65535	The range of ports that can be changed in the registry: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft Speech Server\2.0\AudioConnectionMinPort HKLM\SOFTWARE\Microsoft\Microsoft Speech Server\2.0\AudioConnectionMaxPort
T.38		Port between 1024 and 65535	Ports are hard-coded and cannot be changed in the Globcfg.xml configuration file or in the registry.
UM Web Service	443		Port is configured on the Web site that hosts the Unified Messaging virtual directory. The port can be changed by using IIS Manager.

New in Exchange 2007 Service Pack 1 (SP1)

The release to manufacturing (RTM) version of Exchange 2007 Unified Messaging does not support Network Address Translation (NAT) traversal. Microsoft Exchange Server 2007 Service Pack 1 (SP1) adds support for RTP media to be tunneled through a NAT firewall. However, for this to work, you must also have Office Communications Server 2007 deployed in your environment. If you deploy both Exchange 2007 SP1 and Communications Server 2007 on your network, this deployment will enable Unified Messaging servers to communicate with endpoints outside a NAT firewall. The Unified Messaging server is associated with an Office Communications Server pool and obtains the appropriate authentication tokens from the Communications Server 2007 A/V Authentication service on a computer that is serving that particular Office Communications Server pool.

The A/V Authentication Service is used to allow voice media to traverse NAT devices and firewalls. This is necessary because media gateways handle signaling only and cannot transport voice securely across a NAT device or firewall. When you configure a mediation server in Communications Server 2007, you specify the A/V Edge server on which the A/V Authentication Service is running so that the mediation server will know where to forward the incoming media packets.

For more information about how to deploy Office Communications Server 2007 and Exchange 2007 Unified Messaging, see the following:

The following table describes the port configuration changes that were made in SP1.

Port configuration changes included in SP1

Protocol	TCP Port	UDP Port	Can ports be changed?
SIP (Microsoft Exchange 2007 Unified Messaging Service)	5060 (unsecured) 5061 (secured) The service listens on both ports.		Ports can be changed in the UMRecyclerConfig.xml configuration file.
SIP (UM worker process)	5065 and 5067 for TCP (unsecured). 5066 and 5068 for MTLS (secured)		Ports can be changed in the UMRecyclerConfig.xml configuration file.
RTP		Ports between 1024 and 65535	The range of ports can be changed in the registry: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft Speech Server\2.0\AudioConnectionMinPort HKLM\SOFTWARE\Microsoft\Microsoft Speech Server\2.0\AudioConnectionMaxPort
T.38		Ports between 1024 and 65535	The minimum and maximum ports can be set in the Globcfg.xml configuration file. Remove the comment marks from the following line and set the minimum and maximum port values: <!-- For specifying FAX port ranges - please use the below here parameters <MinFAXPort>port number</MinFAXPort> <MaxFAXPort>port number</MaxFAXPort> -->
UM Web Service	443		The port is configured on the Web site that hosts the Unified Messaging virtual directory. The port can be changed by using IIS Manager.

For More Information

For more information about new Unified Messaging client features, see Client Features in Unified Messaging.

For more information about the Unified Messaging client features that are found in Outlook 2007, see Outlook Features for Exchange Unified Messaging.

For more information about the Play on Phone feature, see Outlook Features for Exchange Unified Messaging: Play on Phone.