The Cisco Unified SIP Phone 3911 provides voice communication over an Internet Protocol (IP) network. The IP Phone functions like a digital business telephone, allowing you to place and receive phone calls and to access features such as mute, hold, transfer, speed dial, and call forward. The IP Phone also supports security features that include image and digest authentication.
The Cisco Unified SIP Phone 3911 is interoperable with RFC-3261, RFC-3264, RFC-3264, RFC-3311, RFC 3515, and RFC-3891.
An IP Phone, like other network devices, must be configured and managed. These phones support G.711a, G.711u, G.729(decode only), and G.729a. This manual describes the Cisco Unified SIP Phone 3911.
CautionUsing a cell, mobile, or GSM phone, or two-way radio in close proximity to a Cisco Unified IP Phone might cause interference. For more information, refer to the manufacturer's documentation of the interfering device.
Understanding the Cisco Unified SIP Phone 3911
Figure 1-1 shows the main components of the Cisco Unified SIP Phone 3911.
Figure 1-1 Cisco Unified SIP Phone 3911
Message Waiting Indicator
Cisco Unified IP Phone Series
What Networking Protocols Are Used?
Cisco Unified IP Phones support several industry-standard and Cisco networking protocols required for voice communication. Table 1-1 provides an overview of the networking protocols supported on the Cisco Unified SIP Phone 3911.
Table 1-1 Supported Networking Protocols on the Cisco Unified IP Phone
Cisco Discovery Protocol (CDP)
CDP is a device-discovery protocol that runs on all Cisco-manufactured equipment.
Using CDP, a device can advertise its existence to other devices and receive information about other devices in the network.
The Cisco Unified IP Phone uses CDP to communicate information such as auxiliary VLAN ID, per port power management details, and Quality of Service (QoS) configuration information with the Cisco Catalyst switch.
Dynamic Host Configuration Protocol (DHCP)
DHCP dynamically allocates and assigns an IP address to network devices.
DHCP enables you to connect an IP phone into the network and have it become operational without you needing to manually assign an IP address or configure additional required network parameters.
DHCP is enabled by default. If disabled, you must manually configure the IP address, subnet mask, gateway, and a TFTP server on each phone locally.
Cisco recommends that you use DHCP custom option 150. With this method, you configure the TFTP server IP address as the option value. For additional supported DCHP configurations, refer Cisco Unified Communications Manager System Guide.
Hypertext Transfer Protocol (HTTP)
HTTP is the standard way of transferring information and moving documents across the Internet and the web.
Cisco Unified SIP Phone 3911 supports HTTP.
Internet Protocol (IP)
IP is a messaging protocol that addresses and sends packets across the network.
To communicate using IP, network devices must have an assigned IP address, subnet, and gateway.
IP addresses, subnets, and gateways identifications are automatically assigned if you are using the Cisco Unified IP Phone with Dynamic Host Configuration Protocol (DHCP). If you are not using DHCP, you must manually assign these properties to each phone locally.
Network Time Protocol (NTP)
NTP is a protocol that is used to synchronize timekeeping among a set of distributed time servers and clients.
When you configure Network Time Protocol (NTP) on Cisco Unified Communications Manager Administration, the Cisco Unified IP phones will get the date and time from an NTP server.
Real-Time Transport (RTP)
RTP is a standard protocol for transporting real-time data, such as interactive voice and video, over data networks.
Cisco Unified IP Phones use the RTP protocol to send and receive real-time voice traffic from other phones and gateways.
Session Description Protocol (SDP)
SDP is the portion of the SIP protocol that determines which parameters are available during a connection between two endpoints. Conferences are established using only the SDP capabilities that are supported by all endpoints in the conference.
SDP capabilities, such as codec types, DTMF detection, and comfort noise are normally configured on a global basis by the Cisco Unified Communications Manager or the Media Gateway in operation. Some SIP endpoints may allow these parameters to be configured on the endpoint itself.
Session Initiation Protocol (SIP)
SIP is the Internet Engineering task Force (IETF) standard for multimedia conferencing over IP. SIP is an ASCII-based, application-layer control protocol (defined in RFC 3261) that can be used to establish, maintain, and terminate calls between two or more endpoints.
Like other VoIP protocols, SIP is designed to address the functions of signaling and session management within a packet telephony network. Signaling allows call information to be carried across network boundaries. Session management provides the ability to control the attributes of an end-to-end call.
Transmission Control Protocol (TCP)
TCP is a connection-oriented transport protocol.
Trivial File Transfer Protocol (TFTP)
TFTP allows you to transfer files over the network.
On the Cisco Unified IP Phone, TFTP enables you to obtain a configuration file specific to the phone type.
TFTP requires a TFTP server in your network, which can be automatically identified from the DHCP server. If you want a phone to use a TFTP server other than the one specified by the DHCP server, you must manually assign the IP address of the TFTP server using the Network Configuration menu on the phone.
User Datagram Protocol (UDP)
UDP is a connectionless messaging protocol for delivery of data packets.
Cisco Unified IP Phones transmit and receive RTP streams, which utilize UDP.
What Features are Supported on the Cisco Unified SIP Phone 3911?
The Cisco Unified SIP Phone 3911 functions much like digital business phones, allowing you to place and receive telephone calls. In addition to traditional telephony features, the Cisco Unified IP Phone includes features that enable you to administer and monitor the phone as a network device.
Cisco Unified IP Phones provide traditional telephony functionality, such as call forwarding and transferring, redialing, speed dialing, and voice messaging system access. Cisco Unified IP phones also provide a variety of other features. For an overview of the telephony features that the Cisco Unified IP Phone supports and for tips on configuring them, see the “Telephony Features Available for the Cisco Unified IP Phone” section.
As with other network devices, you must configure Cisco Unified SIP Phone 3911 so that it can access Cisco Unified Communications Manager and the rest of the IP network. By using DHCP, you have fewer settings to configure on a phone, but if your network requires it, you can manually configure an IP address, TFTP server, and subnet mask. For instructions on configuring the network settings on the Cisco Unified IP Phones, see Chapter4, “Configuring Settings on the Cisco Unified IP Phone”
You can modify additional settings for the Cisco Unified IP Phone from the Cisco Unified Communications Manager Administration application. Use this web-based application to set up phone registration criteria and calling search spaces. See the “Telephony Features Available for the Cisco Unified IP Phone” section, and refer to the Cisco Unified Communications Manager documentation for additional information.
For more information about the Cisco Unified Communications Manager Administration application, refer to Cisco Unified Communications Manager documentation, including Cisco Unified Communications Manager Administration Guide. You can also use the context-sensitive help available within the application for guidance.
You can access the complete Cisco Unified Communications Manager documentation suite at this location:
If you are a system administrator, you are likely the primary source of information for Cisco Unified IP Phone users in your network or company. To ensure that you distribute the most current feature and procedural information, familiarize yourself with Cisco Unified IP Phone documentation. Make sure to visit the Cisco Unified IP Phone web site:
From this site, you can view access various user guides.
In addition to providing documentation, it is important to inform users of available Cisco Unified IP Phone features—including those specific to your company or network—and of how to access and customize those features, if appropriate.
Understanding Security Features for Cisco Unified SIP Phone 3911
Cisco Unified SIP Phone 3911 support the following security feature:
Digest authentication—When the phone makes any request, Cisco Unified Communications Manager issues a challenge that requires the phone to respond with the correct password.
Overview of Configuring and Installing Cisco Unified IP Phones
When deploying a new IP telephony system, system administrators and network administrators must complete several initial configuration tasks to prepare the network for IP telephony service. For information and a checklist for setting up and configuring a complete Cisco Unified IP telephony network, refer to the “System Configuration Overview” chapter in Cisco Unified Communications Manager System Guide.
After you have set up the IP telephony system and configured system-wide features in Cisco Unified Communications Manager, you can add IP phones to the system.
The following topics provide an overview of procedures for adding Cisco Unified IP Phones to your network:
For general information about configuring phones in Cisco Unified Communications Manager, refer to the “Cisco Unified IP Phones” chapter in Cisco Unified Communications Manager System Guide and the “Cisco Unified IP Phone Configuration” chapter in Cisco Unified Communications Manager Administration Guide.
Checklist for Configuring the Cisco Unified IP Phone in Cisco Unified Communications Manager
Table 1-2 provides an overview and checklist of configuration tasks for the Cisco Unified IP Phone in Cisco Unified Communications Manager Administration. The list presents a suggested order to guide you through the phone configuration process. Some tasks are optional, depending on your system and user needs. For detailed procedures and information, refer to the sources in the list.
Table 1-2 Checklist for Configuring the Cisco Unified SIP Phone 3911 in Cisco Unified Communications Manager
For More Information
1. Gather the following information about the phone:
Physical location of the phone
Name or user ID of phone user
Partition, calling search space, and location information
Associated directory number (DN) to assign to the phone
Cisco Unified Communications Manager user to associate with the phone
Provides list of configuration requirements for setting up phones.
Identifies preliminary configuration that you need to perform before configuring individual phones.
Refer to Cisco Unified Communications Manager System Guide, “Cisco Unified IP Phone” chapter.
After you have added the phones to the Cisco Unified Communications Manager database, you can complete the phone installation. You (or the phone users) can install the phone at the users’s location. The Cisco Unified IP Phone Installation Guide that ships in the box with each phone provides directions for connecting the phone handset, cables, and other accessories.
After the phone is connected to the network, the phone startup process begins and the phone registers with Cisco Unified Communications Manager. To finish installing the phone, configure the network settings on the phone depending on whether you enable or disable DHCP service.
If you used auto-registration, you need to update the specific configuration information for the phone such as associating the phone with a user, changing the button table, or directory number.
Checklist for Installing the Cisco Unified IP Phone
Table 1-3 provides an overview and checklist of installation tasks for the Cisco Unified IP Phone. The list presents a suggested order to guide you through the phone installation. Some tasks are optional, depending on your system and user needs. For detailed procedures and information, refer to the sources in the list.
Table 1-3 Checklist for Installing the Cisco Unified SIP Phone 3911