Cisco Unified IP Phones enable you to communicate by using voice over a data network. To provide this capability, IP phones depend upon and interact with several other key Cisco Unified IP Telephony components, including Cisco Unified Communications Manager.
This chapter focuses on the interactions between the Cisco Unified IP Phone 8961, 9951, and 9971 and Cisco Unified Communications Manager, DNS and DHCP servers, TFTP servers, and switches. The chapter also describes phone power options.
For related information about voice and IP communications, see this URL:
This chapter provides an overview of the interaction between the Cisco Unified IP Phone and other key components of the VoIP network.
Cisco Unified IP Communications Product Interactions
To function in the IP telephony network, the Cisco Unified IP
Phone must connect to a network device, such as a Cisco Catalyst
switch. You must also register the Cisco Unified IP Phone with a Cisco
Unified Communications Manager system before sending and receiving calls.
Cisco Unified IP Phone and Cisco Unified Communications Manager Interaction
Cisco Unified Communications Manager is an open,
industry-standard call processing system. Cisco Unified Communications Manager
software sets up and tears down calls between phones, integrating traditional
PBX functionality with the corporate IP network. Cisco Unified Communications
Manager manages the components of the IP telephony system, such as the phones,
the access gateways, and the resources necessary for features such as call
conferencing and route planning. Cisco Unified Communications Manager also
Firmware for phones
Configuration, CTL, and Identity Trust List (ITL) files using the
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 IP Phone
Configuration" chapter in the Cisco Communications Manager Administration Guide.
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:
The Cisco Unified IP Phone 8961, 9951, and 9971 contains an internal Ethernet switch, enabling forwarding of packets to the phone, and to the computer (access) port and the network port on the back of the phone.
If a computer is connected to the computer (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, additional IP addresses might not be available to assign the phone to the same subnet as other devices that connect to the same port.
Data traffic present on the VLAN supporting phones might reduce the quality of VoIP traffic.
Network security may indicate a need to isolate the VLAN voice traffic from the VLAN data traffic.
You can resolve these issues by isolating the voice traffic onto a separate VLAN. The switch port to which the phone connects would be configured for 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 computer (access) port of the IP phone (native VLAN)
Isolating the phones on a separate, auxiliary VLAN increases the quality of the voice traffic and allows a large number of phones to be added to an existing network that does not have enough IP addresses for each phone.
For more information, see the documentation that is included with a Cisco switch. You can also access switch information at this URL:
Cisco Unified IP Phone and Cisco Unified Communications Manager Express Interaction
When the Cisco Unified IP Phone works with the Cisco Unified Communications Manager Express (Unified CME), the phones must go into CME mode.
When a user invokes the conference feature, the tag allows the phone to use either a local or network hardware conference bridge.
The Cisco Unified IP Phones do not support the following actions:
Only supported in the connected call transfer scenario.
Only supported in the connected call transfer scenario.
Supported using the Conference button or Hookflash access.
Supported using the Hold button.
The users cannot create conference and transfer calls across different lines.
Cisco Unified IP Phone Power
The Cisco Unified IP Phone 8961, 9951, and 9971 can be powered with external power or with Power over Ethernet (PoE). A separate power supply provides external power. The switch can provide PoE through the phone Ethernet cable.
When you install a phone that is 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 table provides guidelines for Cisco Unified IP Phone 8961, 9951, and 9971 power.
Table 1 Guidelines for Cisco Unified IP Phone 8961, 9951, and 9971 Power
External power: Provided through the CP-PWR-CUBE-4= external power supply
The Cisco Unified IP Phone 8961, 9951, and 9971 uses the CP-PWR-CUBE-4 power supply.
You must use the CP-PWR-CUBE-4 when you deploy the Cisco Unified IP Phone 9971 on a wireless network.
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.
Cisco Unified IP Phone 8961, 9951, and 9971 supports IEEE 802.3af Class 3 power on signal pairs and spare pairs.
Cisco Unified IP Phone 8961, 9951, and 9971 supports IEEE 802.3at for external add-on devices.
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.
Support for NG-PoE+: The Cisco Unified IP Phone 8961, 9951, and 9971 can draw more power than IEEE 802.3at, as long as there is NG-PoE+ switch support.
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.
Phone Power Reduction
You can reduce the amount of energy that the Cisco Unified IP Phone consumes by using Power Save or EnergyWise (Power Save Plus) mode.
In Power Save mode, the backlight on the screen is not lit when
the phone is not in use. The phone remains in Power Save mode for the scheduled
duration or until the user lifts the handset or presses any button. In the
Phone Configuration window on Cisco Unified Communications Manager Administration,
configure the following parameters:
Days Display Not Active
Specifies the days that the backlight
Display on Time
Schedules the time of day that the backlight
automatically activates. on the days listed in the off schedule.
Display on Duration
Indicates the length of time that the
backlight is active after the backlight is enabled by the programmed schedule.
Display Idle Timeout
Defines the period of user inactivity on the
phone before the backlight is turned off.
In addition to Power Save mode, the Cisco Unified IP Phone
supports Cisco EnergyWise (Power Save Plus) mode. When your network contains an
EnergyWise (EW) controller (for example, a Cisco switch with the EnergyWise
feature enabled), you can configure these phones to sleep (power down) and wake
(power up) on a schedule to further reduce power consumption.
Set up each phone to enable or disable the EnergyWise
settings. If EnergyWise is enabled, configure a sleep and wake time, as
well as other parameters. These parameters are sent to the phone as part of the
phone configuration XML file. In the
Phone Configuration window in Cisco Unified
Communications Manager Administration, configure the following parameters:
Enable Power Save Plus
Selects the schedule of days for which the
phone powers off.
Phone On Time
Determines when the phone automatically turns on for
the days that are selected in the Enable Power Save Plus field.
Phone Off Time
Determines the time of day that the phone powers down for the
days that are selected in the Enable Power Save Plus field.
Phone Off Idle Timeout
Determines the length of time that the phone must be
idle before the phone powers down.
Enable Audio Alert
When enabled, instructs the phone to play an
audible alert starting 10 minutes before the time that the Phone
Off Time field specifies.
Specifies the EnergyWise domain that the phone is in.
Specifies the security secret password that is used to
communicate within the EnergyWise domain.
Allow EnergyWise Overrides
Determines whether you allow the
EnergyWise domain controller policy to send power-level updates to the phones.
When a phone is sleeping, the power sourcing equipment (PSE)
provides minimal power to the phone to illuminate the Select key, and the
Select key can be used to wake up the phone when it is sleeping.
Power Negotiation over LLDP
The phone and the switch negotiate the power that the phone
consumes. Cisco Unified IP Phone 8961, 9951, and 9971 operates at multiple
power settings, which lowers power consumption when less power is available.
After a phone reboots, the switch locks to one protocol (CDP
or LLDP) for power negotiation. The switch locks to the first protocol (containing a
power Threshold Limit Value [TLV]) that the phone transmits. If the system
administrator disables that protocol on the phone, the phone cannot power up any
accessories because the switch does not respond to power requests in the other
Cisco recommends that Power Negotiation always be enabled
(default) when connecting to a switch that supports power negotiation.
If Power Negotiation is disabled, the switch may disconnect power to the phone. If
the switch does not support power negotiation, disable the Power
Negotiation feature before you power up accessories over PoE. When the Power
Negotiation feature is disabled, the phone can power the accessories up to the
maximum that the IEEE 802.3af-2003 standard allows.
When CDP and Power Negotiation are disabled, the phone can power the
accessories up to 15.4W.
Additional Information About Power
The documents in the following table provide more information on the following topics:
Cisco switches that work with Cisco Unified IP Phones
Cisco IOS releases that support bidirectional power negotiation
The TFTP server stores the phone configuration files that define parameters for connecting to Cisco Unified Communications Manager. In general, any time you make a change in Cisco Unified Communications Manager that requires the phone to be reset, a change is automatically made to the configuration file for the phone.
Configuration files also contain information about the image load that the phone should be running. If this image load differs from the one that is currently loaded on a phone, the phone contacts the TFTP server to request the required load files.
A phone accesses a default configuration file, named XmlDefault.cnf.xml, from the TFTP server when the following conditions exist:
You enable autoregistration in Cisco Unified Communications Manager.
You have not added the phone to the Cisco Unified Communications Manager database.
The phone is registering for the first time.
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 makes four attempts to obtain the file so the phone can register securely.
If autoregistration is not enabled and the phone does not exist in the Cisco Unified Communications Manager database, the system rejects the phone registration request and a blank screen displays.
If the phone has registered previously, the phone accesses the SEPmac_address.cnf.xml configuration file, where mac_address is the MAC address of the phone.
The filenames are derived from the MAC address and description fields in the Phone Configuration window of Cisco Unified Communications Manager Administration. The MAC address uniquely identifies the phone.
Phone Startup Process
When connecting to the VoIP network, the
Cisco Unified IP Phone 8961, 9951, and 9971 goes through a standard startup process. Depending on your specific network
configuration, only some of these steps may occur on your Cisco Unified IP Phone.
Obtain power from the switch. If a phone is not using external
power, the switch provides inline power through the Ethernet cable that is attached to
(For a Cisco Unified IP Phone 9971 in a wireless LAN only) Scan
for an access point. The Cisco Unified IP Phone 9971 scans the RF coverage area
with the radio. The phone searches the network profiles and scans for access
points that contain a matching SSID and authentication type. The phone
associates with the access point with the highest RSSI that matches with the
(For a Cisco Unified IP Phone 9971 in a wireless LAN only)
Authenticate with the access point. The Cisco Unified IP Phone begins the
authentication process. The following table describes the authentication
Key management options
Any device can authenticate to the access point. For
added security, static WEP encryption might optionally be used.
The phone encrypts the challenge text by using the WEP key
and the access point must verify the WEP key that was used to encrypt the challenge text
before network access is available.
LEAP or EAP-FAST
The RADIUS server authenticates the username and password before network access is available. For more information about name and password authentication, see
WLAN Setup Menu.
WPA, WPA2, or CCKM
The phone looks for an access point with one of the key
management options enabled. The username and password are authenticated by the
RADIUS server before network access is available.
WPA-Pre-shared key, WPA2-Pre-shared key
The phone looks for an access point that has one of the key
management options enabled. Authentication uses the configured WPA-Pre-shared
key or WPA2-Pre-shared key
Load the stored phone image. The Cisco Unified IP Phone has
nonvolatile flash memory in which the phone stores firmware images and user-defined
preferences. At startup, the phone runs a bootstrap loader that loads a phone
firmware image that is stored in flash memory. Using this image, the phone initializes
the software and hardware.
Configure the VLAN. If the Cisco Unified IP Phone is connected to
a Cisco Catalyst switch, the switch next informs the phone of the voice VLAN
that is defined on the switch. The phone needs to know the VLAN membership before it
can proceed with the Dynamic Host Configuration Protocol (DHCP) request for an
Obtain an IP address. If the Cisco Unified IP Phone is using DHCP
to obtain an IP address, the phone queries the DHCP server to obtain one. If
you are not using DHCP in your network, you must assign static IP addresses to
each phone locally.
Request the CTL file. The TFTP server stores the CTL file. This
file contains the certificates that are necessary for establishing a secure connection
between the phone and Cisco Unified Communications Manager.
For more information, see the Cisco Unified Communications Manager Security Guide,
"Configuring the Cisco CTL Client" chapter.
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 signed by the
servers. Cisco Unified Communications Manager
8.5 and later supports the ITL file.
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.
You can also assign an alternate TFTP server to use instead of
the one that DHCP assigns.
Contact Cisco Unified Communications Manager. The configuration
file defines how the Cisco Unified IP Phone communicates with Cisco Unified CM
and provides a phone with the load ID. After it obtains the file from the TFTP
server, the phone attempts to make a connection to the highest priority Cisco
Unified CM on the list.
If the security profile of the phone is configured for secure
signaling (encrypted or authenticated) and the Cisco Unified Communications
Manager is set to secure mode, the phone makes a TLS connection. Otherwise, the phone
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 itself in
the Cisco Unified Communications Manager database.
Autoregistration is disabled when you configure the CTL client.
In this case, you must add the phone to the Cisco Unified
Communications Manager database manually.
For more information, see
the "Cisco Unified IP Phone and your network" chapter and
the "Troubleshooting and maintenance" chapter.
Before installing the Cisco Unified IP Phone, you must
choose a method for adding phones to the Cisco Unified Communications Manager
The following table provides an overview of the methods
for adding phones to the Cisco Unified Communications Manager database.
Table 2 Methods for Adding Phones to the Cisco Unified Communications
Requires MAC address?
Results in automatic assignment of directory numbers.
Autoregistration with the Tool for Auto-Registered Phones Support (TAPS)
Requires autoregistration and the Bulk Administration Tool
(BAT); updates information in the Cisco Unified IP Phone and in Cisco
Unified Communications Manager Administration.
Using the Cisco Unified Communications Manager Administration
Requires phones to be added individually.
Allows for simultaneous registration of multiple phones.
Autoregistration Phone Addition
By enabling 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
Communications Manager 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.
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, or if you want to use a secure connection with Cisco
Unified Communications Manager as described in
Cisco Unified Communications Manager Security Guide. For
information about enabling autoregistration, see the
"Enabling Autoregistration" section in the
Cisco Unified Communications Manager Administration
Autoregistration and TAPS Phone Addition
You can add phones with autoregistration and TAPS, the Tool
for AutoRegistered Phones Support, without first gathering MAC addresses from
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
to download predefined configurations for phones.
Cisco recommends that you use autoregistration and TAPS to add fewer than
100 phones to your network. To add more than 100 phones to your network, use
the Bulk Administration Tool (BAT).
To implement TAPS, you or the end user dials a TAPS directory
number and follows voice prompts. After the process is complete, the phone
contains the directory number and other settings, and the phone is updated in
Cisco Unified Communications Manager Administration with the correct MAC
Autoregistration must be enabled in Cisco Unified
Communications Manager Administration
(System > Cisco Unified
CM) for TAPS to function.
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
not enabled automatically.
For more information, see the
Cisco Unified Communications Manager Bulk Administration
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 collect 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 Overview" chapter in the
Cisco Unified Communications Manager System Guide.
Add Phones Using BAT Phone Template
The Cisco Unified Communications Bulk Administration Tool
(BAT) enables you to perform batch operations, including registration of
To add phones using BAT only (not in conjunction with TAPS),
you must obtain the appropriate MAC address for each phone.
For detailed instructions about adding phones through the Bulk
Administration menu, see the
Cisco Unified Communications Manager Bulk Administration
Guide, “Inserting Phones” chapter.
For more information about using BAT, see the Cisco Unified Communications
Manager Bulk Administration Guide. For more information about creating of
BAT Phone Templates, see the "Phone Template" section in the Cisco
Unified Communications Manager Bulk Administration Guide.
To add a phone to the Cisco Unified Communications Manager,
follow these steps: