This section describes the hardware and software features of the Cisco Analog Telephone Adaptor (Cisco ATA) and includes a brief overview of the Media Gateway Control Protocol (MGCP).
Cisco ATA analog telephone adaptors are handset-to-Ethernet adaptors which allow regular analog telephones to operate on IP-based telephony networks. Cisco ATAs support two voice ports, each with an independent telephone number. The Cisco ATA 188 also has an RJ-45 10/100BASE-T data port.
The Cisco ATA, which operates with Cisco voice-packet gateways, makes use of broadband pipes that are deployed by means of a digital subscriber line (DSL), fixed wireless cable modem, and other Ethernet connections.
Note The term Cisco ATA refers to both the Cisco ATA 186 and the Cisco ATA 188, unless otherwise stated.
Figure 1-2 The Cisco ATA 186 as an Endpoint in an MGCP Network
Figure 1-3 The Cisco ATA 188 as an Endpoint in an MGCP Network
Overview of Media Gateway Control Protocol
The Media Gateway Control Protocol (MGCP) is the Internet Engineering Task Force (IETF) standard for multimedia conferencing over IP. MGCP is an ASCII-based, application-layer control protocol (defined in RFC2705) that can be used to establish, maintain, and terminate calls between two or more endpoints.
Like other VoIP protocols, MGCP 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.
One aspect of MGCP that differs from other VoIP protocols is that MGCP endpoints rely on instructions from a Call Agent to control call progression, call tones, and call characteristics.
MGCP provides the following capabilities to the control server:
Determines the location of the target endpoint.
Determines the media capabilities of the target endpoint. Using Session Description Protocol (SDP), MGCP determines the lowest level of common service between the endpoints. Conferences are established using only the media capabilities that can be supported by all endpoints.
Determines the availability of the target endpoint.
Establishes a session between the originating and target endpoint if a call can be completed. MGCP also supports mid-call changes, such as adding another endpoint to the conference or changing a media characteristic or codec.
Each MGCP endpoint supports up to two connections per device. Each connection has a fixed ID—0, 1, 2, or 3. Connection IDs 0 and 2 are assigned to MGCP Endpoint 0, and connection IDs 1 and 3 are assigned to MGCP Endpoint 1.
MGCP is a client-server protocol. The Call Agent handles all aspects of setting up calls to and from endpoints. Call Agents or control servers provide the feature capabilities that a particular endpoint uses. Endpoints connected to different Call Agents likely will have a different set of features.
Each control-server vendor determines its own set of features.
Hardware Overview
The Cisco ATA 186 and Cisco ATA 188 are compact, easy-to-install devices. Figure 1-4 shows the rear panel of the Cisco ATA 186. Figure 1-5 shows the rear panel of the Cisco ATA 188.
Figure 1-4 Cisco ATA 186—Rear View
Figure 1-5 Cisco ATA 188—Rear View
The unit provides the following connectors and indicators:
5V power connector.
Two RJ-11 FXS (Foreign Exchange Station) ports—The Cisco ATA supports two independent RJ-11 telephone ports that can connect to any standard analog telephone device. Each port supports either voice calls or fax sessions, and both ports can be used simultaneously.
Note The Cisco ATA186-I1 and Cisco ATA188-I1 provide 600-ohm resistive
impedance. The Cisco ATA186-I2 and Cisco ATA188-I2 provide 270
ohm + 750 ohm // 150-nF complex impedance. The impedance option is requested when you
place your order and should match your specific application. If you are not sure of the applicable
configuration, check your country or regional telephone impedance requirements.
Ethernet ports
The Cisco ATA 186 has one RJ-45 10BASE-T uplink Ethernet port to connect the Cisco ATA 186 to a 10/100BASE-T hub or another Ethernet device.
The Cisco ATA 188 has two Ethernet ports: an RJ-45 10/100BASE-T uplink port to connect the Cisco ATA 188 to a 10/100BASE-T hub or another Ethernet device and an RJ-45 10/100BASE-T data port to connect an Ethernet-capable device, such as a computer, to the network.
Note The Cisco ATA 188 performs auto-negotiation for duplexity and
speed and is capable of 10/100 Mbps, full-duplex operation. The Cisco ATA 186 is fixed at
10 Mbps, half-duplex operation.
The Cisco ATA 188 RJ-45 LED shows network link and activity. The LED blinks twice when the Cisco ATA is first powered on, then turns off if there is no link or activity. The LED blinks to show network activity and is solid when there is a link.
The Cisco ATA 186 RJ-45 LED is solid when the Cisco ATA is powered on and blinks to show network activity.
Function button—The function button is located on the top panel of the unit (see Figure 1-6).
Figure 1-6 Function Button
The function button lights when you pick up the handset of a telephone attached to the Cisco ATA. The button blinks quickly when the Cisco ATA is upgrading its configuration.
Note If the function button blinks slowly, the Cisco ATA cannot find the
DHCP server. Check your Ethernet connections and make sure the DHCP server is available.
Pressing the function button allows you to access to the voice configuration menu. For additional information about the voice configuration menu, see the "Voice Configuration Menu" section.
Caution Never press the function button during an upgrade process. Doing so may interfere with the process and may permanently disable the Cisco ATA.
Software Features
The Cisco ATA supports the following protocols and services:
The Cisco ATA supports the following MGCP versions:
MGCP 0.1
MGCP 1.0
NCS 1.0
Voice Codecs Supported
The Cisco ATA supports the following voice codecs (check your other network devices for the codecs they support):
G.711µ-law
G.711A-law
G.723.1
G.729
G.729A
G.729B
G.729.AB
Additional Supported Signaling Protocols
In addition to MGCP, the Cisco ATA supports the following signaling protocols:
Skinny Client Control Protocol (SCCP)
H.323
Session Initiation Protocol (SIP)
MGCP and SCCP share the same software image. SIP and H.323 also share a software image, which is separate from the SCCP/MGCP image. If you wish to perform a cross-protocol upgrade from MGCP to another signaling image, see the "Upgrading the Signaling Image from a TFTP Server" section.
Other Supported Protocols
Other protocols that the Cisco ATA supports include the following:
802.1Q VLAN tagging
Cisco Discovery Protocol (CDP)
Domain Name System (DNS)
Dynamic Host Configuration Protocol (DHCP)
Internet Control Message Protocol (ICMP)
Internet Protocol (IP)
Real-Time Transport Protocol (RTP)
Transmission Control Protocol (TCP)
Trivial File Transfer Protocol (TFTP)
User Datagram Protocol (UDP)
Cisco ATA MGCP Services
For a list of required MGCP parameters as well as descriptions of all supported Cisco ATA MGCP services and cross references to the parameters for configuring these services, see "Cisco ATA-Supported MGCP Services."
These services include the following features:
Two MGCP endpoints per Cisco ATA
Two connections per MGCP endpoint
Multiple audio codecs
Events and signals available in MGCP software packages
IP address assignment—DHCP-provided or statically configured
Cisco ATA configuration by means of a TFTP server, web browser, or voice configuration menu.
VLAN configuration
Caller ID format
Ring cadence format
Silence suppression
Low-bit-rate codec selection
RTP media port configuration
Hook-flash detection timing configuration
Cisco Discovery Protocol (CDP)
User interface password
UDP Type of Service (ToS) configuration
Debugging and diagnostic tools
Fax Services
The Cisco ATA supports two modes of fax services, in which fax signals are transmitted using the G.711 codec:
Fax pass-through mode—Receiver-side Called Station Identification (CED) tone detection with automatic G.711A-law or G.711µ-law switching.
Fax mode—The Cisco ATA is configured as a G.711-only device.
How you set Cisco ATA fax parameters depends on what network gateways are being used. You may need to modify the default fax parameter values (see "Configuring and Debugging Fax Services").
Note Success of fax transmission depends on network conditions and fax modem response to these conditions.
The network must have reasonably low network jitter, network delay, and packet loss rate.
Supplementary Services that the Cisco ATA Provides
Table 1-1 lists the supplementary phone services that the Cisco ATA provides for MGCP. Table 1-1 includes links to the corresponding parameters that allow you to configure these services.
Table 1-1 Supplementary Services that Require Configuration on the Cisco ATA
