The Cisco Voice Gateway provides VoIP connectivity to analog devices such as analog desk phones, analog conference room phones, fax machines, and modems. This voice gateway provides several improvements from the previous high-density analog and digital extension modules (EVMs) in the following ways:

• On-board Digital Signal Processor (DSP): The FXO and FXS service modules contain an onboard DSP and don’t require the router to have a dedicated packet voice DSP module (PVDM) on the motherboard. The DSP on the voice module is necessary for the voice features. It also provides for echo cancellation of up to 128-ms echo-tail length for demanding network conditions.

• Support for Online Insertion and Removal (OIR): The FXS and FXO service modules support Online Insertion and Removal (OIR), reducing the downtime required for new or replacement modules. The service modules can be inserted into the NIM slot on the device without powering off the voice gateway.

• FXS-E (extended loops) support: FXS ports on the new modules support FXS-E with the following details:

  • Higher loop current (35 mA) to accommodate specialty phones

  • Longer loop length for loops with 26 AWG wire, up to 11,000 feet (3400 meters)

  • Higher ringing voltage (65 Vrms, no load)

In addition to these features, the following are also supported:

• Caller line ID

• G.711, G.729a, and G.726

• G722, iLBC

• Fax detection, pass-through, and relay (T.38)

• Modem pass-through

• DTMF detection

• Echo cancellation

• Voice activity detection

• Comfort noise generation

• Real-Time Control Protocol (RTCP)

• Acoustic shock protection

• Real-Time Transport Protocol (RTP)

• RFC 4733 Digit Relay

• Noise reduction

The FXS features include:

• Support for either FXS or DID functionality

• Message-Waiting Indicator (MWI)

• Cable detection: GR909 line test

The FXO features include:

• Support for both ground-start and loop-start modes

• Call Detail Record (CDR) information

• Support for interworking with Cisco Unified Communications Manager (Skinny Client Control Protocol [SCCP]), Session Initiation Protocol (SIP), and Media Gateway Control Protocol (MGCP) 0.1

• Cable detection

• Overload protection

• Analog phone connectivity

• Fax and modem connectivity

The Cisco VG420 Voice Gateway supports the following protocols:

• SCCP

• MGCP

• SIP

• Real-Time Transport Protocol (RTP)

• Secure Real-Time Transport Protocol (SRTP)

• Trivial File Transfer Protocol (TFTP)

• HTTP Server

• Simple Network Management Protocol (SNMP)

• Telnet

• Dynamic Host Configuration Protocol (DHCP)

• DNS

• T.38 fax relay and modem pass-through

• RADIUS and TACACS+ for Telnet and authorization

The following images show the I/O and side panel views of the Cisco VG420 Voice Gateway chassis:

The following table specifies the Cisco VG420 Voice Gateway SKU information. All the SKUs support the following external interfaces:

The following are the NIM models that are supported by Cisco VG420 Voice Gateway:

NIM-1MFT-T1/E1

NIM-2MFT-T1/E1

NIM-4MFT-T1/E1

NIM-8MFT-T1/E1

NIM-4E/M

NIM-2FXO

NIM-4FXO

NIM-2FXSP

NIM-4FXSP

NIM-2FXS/4FXOP

NIM-2BRI-NT/TE

NIM-4BRI-NT/TE

The following image represents the NIM slots:

Use the Cisco Product Identification (CPI) tool to find labels on the platform. The tool provides detailed illustrations and descriptions of where labels are located on Cisco products. It includes the following features:

• A search option that allows browsing for models by using a tree-structured product hierarchy.

• A search field on the final results page that makes it easier to look up multiple products.

• End-of-sale products clearly identified in results lists.

The tool streamlines the process of locating the serial number labels and identifying products. Serial number information expedites the entitlement process and is required to access support services.

The following image shows the location of the labels on the voice gateway.

The Serial number (SN), Common language equipment identifier (CLEI), Top Assembly Number (TAN), Product ID (PID), PID version ID (VID), and Quick response (QR) code are printed on a label at the bottom of the hardware or on a label tray located on the chassis.

To access the Cisco VG420 Voice Gateway technical specifications, see the Cisco VG420 Voice Gateway Datasheet.