Technical Details
Physical and Operating Environment Specifications
The following table shows the physical and operating environment specifications for the Cisco IP Phone 6800 Series Multiplatform Phones.
For detailed technical information about the phone, see the datasheet at:
Cable Specifications
Network and Computer Port Pinouts
Network Port Connector
The following table describes the network port connector pinouts.
Pin Number |
Function |
||
|---|---|---|---|
1 |
BI_DA+ |
||
2 |
BI_DA- |
||
3 |
BI_DB+ |
||
4 |
BI_DC+ |
||
5 |
BI_DC- |
||
6 |
BI_DB- |
||
7 |
BI_DD+ |
||
8 |
BI_DD- |
||
|
|||
Computer Port Connector
The following table describes the computer port connector pinouts.
Pin Number |
Function |
||
|---|---|---|---|
1 |
BI_DB+ |
||
2 |
BI_DB- |
||
3 |
BI_DA+ |
||
4 |
BI_DD+ |
||
5 |
BI_DD- |
||
6 |
BI_DA- |
||
7 |
BI_DC+ |
||
8 |
BI_DC- |
||
|
|||
Phone Power Requirements
The Cisco IP Phone 6841 is powered by external power. The Cisco IP Phone 6851 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.
 Note | 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. |
|
Power Type |
Guidelines |
|---|---|
|
External power: Provided through the external power supply |
The Cisco IP Phone 6841 and 6851 use a custom power supply. |
|
External power—Provided through the Cisco IP Phone Power Injector |
The Cisco IP Phone Power Injector may be used with the Cisco IP Phone 6851. Functioning as a midspan device, the injector delivers inline power to the attached phone. The Cisco 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 Cisco IP Phone 6851. |
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. |
The documents in the following table provide more information on the following topics:
-
Cisco switches that work with Cisco IP Phones
-
Cisco IOS releases that support bidirectional power negotiation
-
Other requirements and restrictions about power
|
Document topics |
URL |
|---|---|
|
PoE Solutions |
|
|
Cisco Catalyst Switches |
http://www.cisco.com/c/en/us/products/switches/index.html |
|
Integrated Service Routers |
http://www.cisco.com/c/en/us/products/routers/index.html |
|
Cisco IOS Software |
http://www.cisco.com/c/en/us/products/ios-nx-os-software/index.html |
Network Protocols
Cisco IP Phones support several industry-standard and Cisco network protocols that are required for voice communication. The following table provides an overview of the network protocols that the phones support.
|
Network Protocol |
Purpose |
Usage Notes |
|---|---|---|
|
Bootstrap Protocol (BootP) |
BootP enables a network device, such as the Cisco IP Phone, to discover certain startup information, such as its IP address. |
— |
|
Cisco Discovery Protocol (CDP) |
CDP is a device-discovery protocol that runs on all Cisco-manufactured equipment. A device can use CDP to advertise its existence to other devices and receive information about other devices in the network. |
The Cisco 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. |
|
Domain Name Server (DNS) |
DNS translates domain names to IP addresses. |
Cisco IP Phones have a DNS client to translate domain names into IP addresses. |
|
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 the phone become operational without the need to manually assign an IP address or to configure additional network parameters. |
DHCP is enabled by default. If disabled, you must manually configure the IP address, subnet mask, and gateway on each phone locally. We recommend that you use the DHCP custom option 160, 159. |
|
Hypertext Transfer Protocol (HTTP) |
HTTP is the standard protocol for transfer of information and movement of documents across the Internet and the web. |
Cisco IP Phones use HTTP for XML services, provisioning, upgrade and for troubleshooting purposes. |
Hypertext Transfer Protocol Secure (HTTPS) |
Hypertext Transfer Protocol Secure (HTTPS) is a combination of the Hypertext Transfer Protocol with the SSL/TLS protocol to provide encryption and secure identification of servers. |
Web applications with both HTTP and HTTPS support have two URLs configured. Cisco IP Phones that support HTTPS choose the HTTPS URL. A lock icon is displayed to the user if the connection to the service is via HTTPS. |
|
Internet Protocol (IP) |
IP is a messaging protocol that addresses and sends packets across the network. |
To communicate with 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 IP Phone with Dynamic Host Configuration Protocol (DHCP). If you are not using DHCP, you must manually assign these properties to each phone locally. |
|
Link Layer Discovery Protocol (LLDP) |
LLDP is a standardized network discovery protocol (similar to CDP) that is supported on some Cisco and third-party devices. |
The Cisco IP Phone supports LLDP on the PC port. |
|
Link Layer Discovery Protocol-Media Endpoint Devices (LLDP-MED) |
LLDP-MED is an extension of the LLDP standard developed for voice products. |
The Cisco IP Phone supports LLDP-MED on the SW port to communicate information such as: For more information about LLDP-MED support, see the LLDP-MED and Cisco Discovery Protocol white paper at this URL: http://www.cisco.com/en/US/tech/tk652/tk701/technologies_white_paper0900aecd804cd46d.shtml |
|
Network Transport Protocol (NTP) |
NTP is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks. |
Cisco IP Phones have an NTP client integrated into the software. |
|
Real-Time Transport Protocol (RTP) |
RTP is a standard protocol for transporting real-time data, such as interactive voice and video, over data networks. |
Cisco IP Phones use the RTP protocol to send and receive real-time voice traffic from other phones and gateways. |
|
Real-Time Control Protocol (RTCP) |
RTCP works in conjunction with RTP to provide QoS data (such as jitter, latency, and round trip delay) on RTP streams. |
RTCP is disabled by default. |
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 by using only the SDP capabilities that all endpoints in the conference support. |
SDP capabilities, such as codec types, DTMF detection, and comfort noise, are normally configured on a global basis by a Third-Party Call Control System or a Media Gateway in operation. Some SIP endpoints may allow configuration of these parameters 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. |
|
Secure Real-Time Transfer protocol (SRTP) |
SRTP is an extension of the Real-Time Protocol (RTP) Audio/Video Profile and ensures the integrity of RTP and Real-Time Control Protocol (RTCP) packets providing authentication, integrity, and encryption of media packets between two endpoints. |
Cisco IP Phones use SRTP for media encryption. |
|
Transmission Control Protocol (TCP) |
TCP is a connection-oriented transport protocol. |
— |
|
Transport Layer Security (TLS) |
TLS is a standard protocol for securing and authenticating communications. |
When security is implemented, Cisco IP Phones use the TLS protocol when securely registering with the third-party call control system. |
|
Trivial File Transfer Protocol (TFTP) |
TFTP allows you to transfer files over the network. On the Cisco 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. |
|
User Datagram Protocol (UDP) |
UDP is a connectionless messaging protocol for delivery of data packets. |
UDP is used only for RTP streams. SIP uses UDP, TCP, and TLS. |
VLAN Interaction
The Cisco IP Phone 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:
http://cisco.com/en/US/products/hw/switches/index.html
External Devices
We recommend that you use good-quality external devices that are shielded against unwanted radio frequency (RF) and audio frequency (AF) signals. External devices include headsets, cables, and connectors.
Depending on the quality of these devices and their proximity to other devices, such as mobile phones or two-way radios, some audio noise may still occur. In these cases, we recommend that you take one or more of these actions:
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Move the external device away from the source of the RF or AF signals.
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Route the external device cables away from the source of the RF or AF signals.
-
Use shielded cables for the external device, or use cables with a better shield and connector.
-
Shorten the length of the external device cable.
-
Apply ferrites or other such devices on the cables for the external device.
Cisco cannot guarantee the performance of external devices, cables, and connectors.
 Caution | In European Union countries, use only external speakers, microphones, and headsets that are fully compliant with the EMC Directive [89/336/EC]. |
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