Cisco Unified IP Phones and Telephony Networks

Phone and Telephony Network Overview

Cisco Unified IP Phones enable you to communicate by using voice over a data network. To provide this capability, the IP phones depend upon and interact with several other key Cisco Unified IP Telephony and network components, including Cisco Unified Communications Manager, DNS and DHCP servers, TFTP servers, media resources, Cisco PoE, and others.

This chapter focuses on the interactions between the Cisco Unified IP Phone 7975G, 7971G-GE, 7970G, 7965G, and 7945G and Cisco Unified Communications Manager, DNS and DHCP servers, TFTP servers, and switches. It also describes options for powering phones.

For related information about voice and IP communications, see this URL:

http://www.cisco.com/en/US/products/sw/voicesw/index.html

This chapter provides an overview of the interaction between the Cisco Unified IP Phone and other key components of the Voice over IP (VoIP) network.

Cisco Unified IP Communications Product Interactions

To function in the IP telephony network, the Cisco Unified IP Phone must be connected to a networking device, such as a Cisco Catalyst switch. You must also register the Cisco Unified IP Phone with a Cisco Unified Communications Manager system before the phone can send and receive calls.

This section includes these topics:

Cisco Unified IP Phone and Cisco Unified Communications Manager Interactions

Cisco Unified Communications Manager is an open and industry-standard call processing system. Cisco Unified Communications Manager software sets up and tears down calls between phones, thus integrating traditional PBX functionality with the corporate IP network. Cisco Unified Communications Manager manages the components of the IP telephony system—the phones, the access gateways, and the resources necessary for features such as call conferencing and route planning. Cisco Unified Communications Manager also provides:

  • Firmware for phones

  • Authentication and encryption (if configured for the telephony system)

  • Configuration, CTL, and Identity Trust List (ITL) files via the TFTP service

  • Phone registration

  • Call preservation, so that a media session continues if signaling is lost between the primary Communications Manager and a phone

For information about configuring Cisco Unified Communications Manager to work with the IP devices described in this chapter, see the Cisco Unified Communications Manager Administration Guide, the Cisco Unified Communications Manager System Guide, and the Cisco Unified Communications Manager Security Guide.


Note

If the Cisco Unified IP Phone model that you want to configure does not appear in the Phone Type drop-down list in Cisco Unified Communications Manager Administration, go to the following URL and install the latest support patch for your version of Cisco Unified Communications Manager:

http://www.cisco.com/kobayashi/sw-center/sw-voice.shtml

Cisco Unified IP Phone and VLAN Interaction

The Cisco Unified IP Phone 7975G, 7971G-GE, 7970G, 7965G, and 7945G have an internal Ethernet switch, which enables forwarding of packets to the phone and to the access port and the network port on the back of the phone.

If a computer is connected to the access port, the computer and the phone share the same physical link to the switch and share the same port on the switch. This shared physical link has the following implications for the VLAN configuration on the network:

  • The current VLANs might be configured on an IP subnet basis. However, an additional IP address might not be available to assign the phone to the same subnet as other devices connect to the same port.

  • Data traffic present on the data/native VLAN may reduce the quality of VoIP traffic.

  • Network security may indicate a need to isolate the VLAN voice traffic from the VLAN data traffic.

Resolve these issues by isolating the voice traffic onto a separate VLAN. The switch port to which the phone connects would be configured to have separate VLANs for carrying:

  • Voice traffic to and from the IP phone (auxiliary VLAN, on the Cisco Catalyst 6000 series, for example)

  • Data traffic to and from the PC that connects to the switch through the access port of the IP phone (native VLAN)

Isolation of the phones on a separate, auxiliary VLAN improves the quality of the voice traffic and allows a large number of phones to be added to an existing network where not enough IP addresses exist for each phone.

For more information, see the documentation included with a Cisco switch. You can also access related documentation at this URL:

http://cisco.com/en/US/products/hw/switches/index.html

Cisco Unified IP Phone Power

Cisco Unified IP Phone 7975G, 7971G-GE, 7970G, 7965G, and 7945G can be powered with external power or with Power over Ethernet (PoE). A separate power supply provides external power. A switch through the Ethernet cable that is attached to a phone provides PoE.


Caution

When you install a phone powered with external power, connect the power supply to the phone and to a power outlet before you connect the Ethernet cable to the phone. When you remove a phone that is powered with external power, disconnect the Ethernet cable from the phone before you disconnect the power supply.

The following sections provide more information about phone power:

Power Guidelines

The following table provides guidelines that apply to external power and to PoE power for Cisco Unified IP Phone 7975G, 7971G-GE, 7970G, 7965G, and 7945G.

Table 1. Guidelines for Powering the Cisco Unified IP Phone 7975G, 7971G-GE, 7970G, 7965G, and 7945G

Power type

Guidelines

External power: Provided through the CP-PWR-CUBE-3 external power supply

The Cisco Unified IP Phone 7975G, 7971G-GE, 7970G, 7965G, and 7945G use the CP-PWR-CUBE-3 power supply.

External power: Provided through the Cisco Unified IP Phone Power Injector

The Cisco Unified IP Phone Power Injector may be used with any Cisco Unified IP Phone. Functioning as a midspan device, the injector delivers inline power to the attached phone. The Cisco Unified IP Phone Power Injector connects between a switch port and the IP phone, and supports a maximum cable length of 100m between the unpowered switch and the IP phone.

PoE power: Provided by a switch through the Ethernet cable attached to the phone

The Cisco Unified IP Unified IP Phone 7975G, 7971G-GE, 7970G, 7965G, and 7945G supports IEEE 802.3af Class 3 power on signal pairs and spare pairs.

The Cisco Unified IP Unified IP Phone 7975G, 7971G-GE, 7970G, 7965G, and 7945G does not support Cisco inline PoE.

To ensure uninterruptible operation of the phone, make sure that the switch has a backup power supply.

Make sure that the CatOS or IOS version that runs on your switch supports your intended phone deployment. See the documentation for your switch for operating system version information.

Phone Power Consumption and Display Brightness

The power consumed by a phone depends on its power configuration. The following table provides a power configuration overview with the maximum power consumed by a phone for each configuration option and the correlating phone screen brightness level.


Note

Power consumption values shown in the table include power losses in the cable that connects the phone to the switch.

Table 2. Power Consumption and Display Brightness for Power Configurations

Phone model

Power configuration

Max. power consumed from a switch

Phone screen brightness

Cisco Unified IP Phone 7975G, 7965G, 7945G

IEEE 802.3af Class 3 power from a Cisco switch, with bidirectional power negotiation enabled

12 W

Full

External power

—

Full

Cisco Unified IP Phone 7971G-GE

IEEE 802.3af Class 3 power from a Cisco switch (with or without bidirectional power negotiation enabled) or from a third-party switch

15.4 W

Near full

External power

—

Full

Cisco Unified IP Phone 7970G

Cisco prestandard PoE from a switch that supports a maximum of 7 W power per port, with bidirectional power negotiation enabled

6.3 W

Approx. 1/2

Cisco prestandard PoE from a Cisco Switch that supports 7 W or 15.4 W power per port, without bidirectional power negotiation

6.3 W

Approx. 1/2

IEEE 802.3af Class 3 power from a Cisco switch, without bidirectional power negotiation

6.3 W

Approx. 1/2

IEEE 802.3af Class 3 power from a third-party switch

6.3 W

Approx. 1/2

IEEE 802.3af Class 3 power from a Cisco switch, with bidirectional power negotiation enabled

10.25 W

Full (see note)

Cisco prestandard PoE from a Cisco Switch that supports 15.4 W power per port, with bidirectional power negotiation enabled

10.25 W

Full

External power

—

Full


Note

Starts at approximately 1/2 brightness, then changes to full brightness when the phone negotiates additional power.

When a phone is powered with a method that does not support full brightness for the phone screen, the phone Brightness control (Settings > User Preferences > Brightness) does not allow you to set the brightness to the maximum value.

Power Outage

Your access to emergency service through the phone requires the phone to receive power. If an interruption in the power supply occurs, Service and Emergency Calling Service dialing do not function until power is restored. In the case of a power failure or disruption, you may need to reset or reconfigure equipment before you can use the Service or Emergency Calling Service dialing.

Additional Information About Power

The documents in the following table provide more information on the following topics:

  • Cisco switches that work with the Cisco Unified IP Phone 7975G, 7971G-GE, 7970G, 7965G, and 7945G

  • Cisco IOS releases that support bidirectional power negotiation

  • Other power requirements and restrictions

Document Topics

URL

Cisco Unified IP Phone Power Injector

http://www.cisco.com/en/US/products/hw/phones/ps379/prod_installation_guides_list.html

PoE Solutions

http://www.cisco.com/en/US/netsol/ns340/ns394/ns147/ns412/index.html

Cisco Catalyst Switches

http://www.cisco.com/en/US/products/hw/switches/ps708/tsd_products_support_series_home.html

Integrated Service Routers

http://www.cisco.com/en/US/products/hw/routers/index.html

Cisco IOS Software

http://www.cisco.com/en/US/products/sw/iosswrel/products_ios_cisco_ios_software_category_home.html

Phone Configuration Files

Phone configuration files are stored on the TFTP server and define Cisco Unified Communications Manager connection parameters. In general, whenever you make a change in Cisco Unified Communications Manager that requires the phone to reset, a change is made automatically to the phone configuration file.

Configuration files also contain information about the image load that the phone should be running. If this image load differs from the one currently that is loaded on a phone currently, the phone contacts the TFTP server to request the required load files. These load files are digitally signed to ensure the authenticity of the file source.

In addition, if the device security mode in the configuration file is set to Authenticated and the CTL file on the phone has a valid certificate for Cisco Unified Communications Manager, the phone establishes a TLS connection to Cisco Unified Communications Manager. Otherwise, the phone establishes a TCP connection. For SIP phones, a TLS connection requires that the transport protocol in the phone configuration file be set to TLS, which corresponds to the transport type in the SIP Security Profile in Cisco Unified Communications Manager Administration.


Note

If the device security mode in the configuration file is set to Authenticated or Encrypted but the phone has not received a CTL or ITL file, the phone tries four times to obtain the file so it can register securely.


Note

Cisco Extension Mobility Cross Cluster is an exception, in that the phone permits a TLS connection to Cisco Unified Communications Manager for secure signaling even without the CTL file.

If you configure security-related settings in Cisco Unified Communications Manager Administration, the phone configuration file contains sensitive information. To ensure the privacy of a configuration file, you must configure it for encryption. For more information, see the Cisco Unified Communications Manager Security Guide, "Configuring Encrypted Phone Configuration Files" chapter.

A phone requests a configuration file whenever it resets and registers with Cisco Unified Communications Manager.

A phone accesses a default configuration file named XmlDefault.cnf.xml only when the phone has not received a valid Trust List file that contains a certificate assigned to Cisco Unified Communications Manager and TFTP.

If autoregistration is not enabled and you did not add the phone to the Cisco Unified Communications Manager database, the phone system rejects the phone registration request with Cisco Unified Communications Manager. The phone displays the Configuring IP message continuously until you either enable autoregistration or add the phone to the Cisco Unified Communications Manager database.

If the phone has registered previously, the phone accesses the configuration file named SEPmac_address.cnf.xml, where mac_address is the MAC address of the phone.

For SIP phones, the TFTP server generates these SIP configuration files:

  • SIP IP Phone

    • For unsigned and unencrypted files: SEP<mac>.cnf.xml

    • For signed files: SEP<mac>.cnf.xml.sgn

    • For signed and encrypted files: SEP<mac>.cnf.xml.enc.sgn

  • Dial Plan: <dialplan>.xml

  • Softkey Template: <softkey_template>.xml

The filenames derive from the MAC Address and Description fields in the Phone Configuration window of Cisco Unified Communications Manager. The MAC address uniquely identifies the phone. For more information, see the Cisco Unified Communications Manager Administration Guide.

For more information about the phone interaction with the TFTP server, see the Cisco Unified Communications Manager System Guide, "Cisco TFTP" chapter.

Phone Startup Process

When the Cisco Unified IP Phone connects to the VoIP network, the phone goes through a standard startup process that the following steps describe. Depending on your specific network configuration, not all of these process steps may occur on your Cisco Unified IP Phone.

Procedure

Step 1

Obtain power from the switch.

If a phone is not using external power, the switch provides in-line power through the Ethernet cable that is attached to the phone.

See Cisco Unified IP Phone Power and Startup Problems.

Step 2

Load the StoredPhone Image.

The Cisco Unified IP Phone has nonvolatile flash memory in which it stores firmware images and user-defined preferences. At startup, the phone runs a bootstrap loader that loads a phone image stored in flash memory. The phone uses this image to initialize its software and hardware.

See Startup Problems.

Step 3

Configure VLAN.

If the Cisco Unified IP Phone is connected to a Cisco switch, the switch next informs the phone of the voice VLAN defined on the switch port. The phone needs to know its VLAN membership before it can proceed with the Dynamic Host Configuration Protocol (DHCP) request for an IP address.

See Network Configuration Menu and Startup Problems.

Step 4

Obtain an IP Address.

If the Cisco Unified IP Phone uses DHCP to obtain an IP address, the phone queries the DHCP server to obtain one. If you do not use DHCP in your network, you must assign static IP addresses to each phone locally.

See Network Configuration Menu and Startup Problems.

Step 5

Access a TFTP Server.

In addition to assigning an IP address, the DHCP server directs the Cisco Unified IP Phone to a TFTP server. If the phone has a statically defined IP address, you must configure the TFTP server locally on the phone. The phone then contacts the TFTP server directly.

Note 

You can also assign an alternative TFTP server to use instead of the one that DHCP assigns.

See Network Configuration Menu and Startup Problems.

Step 6

Request the CTL file.

The TFTP server stores the CTL file. This file contains the certificates that are necessary to establish a secure connection between the phone and Cisco Unified Communications Manager.

See the Cisco Unified Communications Manager Security Guide, “Configuring the Cisco CTL Client” chapter.

Step 7

Request the ITL file.

The phone requests the ITL file after it requests the CTL file. The ITL file contains the certificates of the entities that the phone can trust. The certificates are used to authenticate a secure connection with the servers or to authenticate a digital signature that the servers sign.

See the Cisco Unified Communications Manager Security Guide, “Security by Default” chapter.

Step 8

Request the Configuration File.

The TFTP server has configuration files, which define parameters for connecting to Cisco Unified Communications Manager and other information for the phone.

See Phone Configuration Files and Startup Problems.

Step 9

Contact Cisco Unified Communications Manager.

The configuration file defines how the Cisco Unified IP Phone communicates with Cisco Unified Communications Manager and provides a phone with the load ID. After the phone obtains the file from the TFTP server, the phone attempts to make a connection to the highest priority Cisco Unified Communications Manager on the list. If the security profile of the phone is configured for secure signaling (encrypted or authenticated), and Cisco Unified Communications Manager is set to secure mode, the phone makes a TLS connection. Otherwise, it makes a nonsecure TCP connection.

If the phone was manually added to the database, Cisco Unified Communications Manager identifies the phone. If the phone was not manually added to the database and autoregistration is enabled in Cisco Unified Communications Manager, the phone attempts to autoregister in the Cisco Unified Communications Manager database.

Note 

Autoregistration is disabled when you configure the CTL client. In this case, the phone must be manually added to the Cisco Unified Communications Manager database.

See Phone Configuration Files and Startup Problems.

Cisco Unified Communications Manager Phone Addition Methods

Before you install the Cisco Unified IP Phone, you must choose a method for adding phones to the Cisco Unified Communications Manager database.

The following table provides an overview of the methods for adding phones to the Cisco Unified Communications Manager database.

Table 3. Cisco Unified Communications Manager Phone Addition Methods

Method

Requires MAC address?

Notes

Autoregistration

No

Results in automatic assignment of directory numbers.

Not available when security or encryption is enabled.

Autoregistration with TAPS

No

Requires autoregistration and the Bulk Administration Tool (BAT); updates the Cisco Unified Communications Manager database with the MAC address and DNs for the device when user calls TAPS from the phone.

Use Cisco Unified Communications Manager Administration

Yes

Requires phones to be added individually.

Use BAT

Yes

Can add groups of same model of phone.

Can schedule when phones are added to the Cisco Unified Communications Manager database.

Autoregistration Phone Addition

If you enable autoregistration before you begin installing phones, you can:

  • Add phones without first gathering MAC addresses from the phones.

  • Automatically add a Cisco Unified IP Phone to the Cisco Unified CM database when you physically connect the phone to your IP telephony network. During autoregistration, Cisco Unified Communications Manager assigns the next available sequential directory number to the phone.

  • Quickly enter phones into the Cisco Unified Communications Manager database and modify any settings, such as the directory numbers, from Cisco Unified Communications Manager.

  • Move autoregistered phones to new locations and assign them to different device pools without affecting their directory numbers.


Note

Cisco recommends that you use autoregistration to add fewer than 100 phones to your network. To add more than 100 phones to your network, use the Bulk Administration Tool (BAT).

Autoregistration is disabled by default. In some cases, you might not want to use autoregistration; for example, if you want to assign a specific directory number to the phone. For information about enabling autoregistration, see "Enable autoregistration" section in the Cisco Unified Communications Manager Administration Guide.


Note

When you configure the cluster for mixed mode through the Cisco CTL client, autoregistration is automatically disabled. When you configure the cluster for nonsecure mode through the Cisco CTL client, autoregistration is automatically enabled.

Autoregistration and TAPS Phone Addition

You can add phones with autoregistration and TAPS, the Tool for Auto-Registered Phones Support, without first gathering MAC addresses from phones.

TAPS works with the Bulk Administration Tool (BAT) to update a batch of phones that were already added to the Cisco Unified Communications Manager database with dummy MAC addresses. Use TAPS to update MAC addresses and download predefined configurations for phones.


Note

Cisco recommends that you use autoregistration and TAPS to add less than 100 phones to your network. To add more than 100 phones to your network, use the Bulk Administration Tool (BAT).

To implement TAPS, dial a TAPS directory number and follow the voice prompts. When the process completes, the phone has downloaded the directory number and other settings, and the phone is updated in Cisco Unified Communications Manager Administration with the correct MAC address.

Autoregistration must be enabled in Cisco Unified Communications Manager Administration (System > Cisco Unified CM) for TAPS to function.


Note

When you configure the cluster for mixed mode through the Cisco CTL client, autoregistration is automatically disabled. When you configure the cluster for nonsecure mode through the Cisco CTL client, autoregistration is automatically enabled.

For more information, see "Bulk Administration" chapter in the Cisco Unified Communications Manager Administration Guide and the "Tool for Auto-Registered Phones Support" chapter in the Cisco Unified Communications Manager Bulk Administration Guide.

Cisco Unified Communications Manager Administration Phone Addition

You can add phones individually to the Cisco Unified Communications Manager database by using Cisco Unified Communications Manager Administration. To do so, you first need to obtain the MAC address for each phone.

After you have collected MAC addresses, in Cisco Unified Communications Manager Administration, choose Device > Phone and click Add New to begin.

For complete instructions and conceptual information about Cisco Unified Communications Manager, see the Cisco Unified Communications Manager Administration Guide and the Cisco Unified Communications Manager System Guide.

Add Phones with BAT

Cisco Unified Communications Bulk Administration Tool (BAT), which is a menu option in Cisco Unified Communications Manager Administration, enables you to perform batch operations, which includes registration of multiple phones.

To add phones by using BAT only (not in conjunction with TAPS), you first need to obtain the appropriate MAC address for each phone.

To add a phone to Cisco Unified Communications Manager, follow these steps:

Procedure

Step 1

From Cisco Unified Communications Manager, choose Bulk Administration > Phones > Phone Template.

Step 2

Click Add New.

Step 3

Choose a Phone Type and click Next.

Step 4

Enter the details of phone specific parameters, such as Device Pool, Phone Button Template, and Device Security Profile.

Step 5

Click Save.

Step 6

From Cisco Unified Communications Manager, choose Device > Phone > Add New to add a phone by using an already created BAT phone template.

For detailed instructions about using BAT, see the Cisco Unified Communications Manager Bulk Administration Guide. For more information on creation of BAT Phone Templates, see the Cisco Unified Communications Manager Bulk Administration Guide, “Phone Template” chapter.

Cisco Unified IP Phones and Different Protocols

The Cisco Unified IP Phones can operate with Skinny Client Control Protocol (SCCP) or Session Initiation Protocol (SIP). You can convert a phone from using one protocol to using the other protocol.

Convert New Phone from SCCP to SIP

A new, unused phone is set for SCCP by default. To convert this phone to SIP, perform these steps:

Procedure

Step 1

Take one of these actions:

  1. To autoregister the phone, set the Auto Registration Phone Protocol parameter in Cisco Unified Communications Manager Administration to SIP.

  2. To provision the phone by using the Bulk Administration Tool (BAT), choose the appropriate phone model and choose SIP from the BAT.

  3. To provision the phone manually, make the appropriate changes for SIP on the Phone configuration window in Cisco Unified Communications Manager Administration.

    For more information about Cisco Unified Communications Manager Administration, see the Cisco Unified Communications Manager Administration Guide. For more information about BAT, see the Cisco Unified Communications Manager Bulk Administration Guide.

Step 2

If you are not using DHCP in your network, configure the network parameters for the phone.

Step 3

Save the configuration updates and perform the following:

  1. Click Apply Config.

  2. When the Apply Configuration Information window displays, click OK.

  3. Power cycle the phone.

In-Use Phone Protocol to Protocol Conversion

For information on how to convert an in-use phone from one protocol to the other, see the Cisco Unified Communications Manager Administration Guide, "Cisco Unified IP Phone Configuration" chapter, "Migrate existing phone settings to another phone" section.

Deploy Phone in SCCP and SIP Environment

To deploy Cisco Unified IP Phones in an environment that includes SCCP and SIP and in which the Cisco Unified Communications Manager autoregistration parameter specifies SCCP, perform these general steps:

Procedure

Step 1

Set the Cisco Unified Communications Manager auto_registration_protocol parameter to SCCP.

Step 2

From Cisco Unified Communications Manager, choose System > Enterprise Parameters.

Step 3

Install the phones.

Step 4

Change the Auto Registration Protocol enterprise parameter to SIP.

Step 5

Autoregister the SIP phones.

Cisco Unified IP Phone MAC Address Determination

Several of the procedures in this manual require you to determine the MAC address of a Cisco Unified IP Phone. You can determine the MAC address for a phone in any of these ways:

  • From the phone, choose Settings > Network Configuration and view the MAC Address field.

  • Look at the MAC label on the back of the phone.

  • Display the web page for the phone and click the Device Information hyperlink.