Features and Benefits of Cisco VG400 Voice Gateway
Cisco VG400 Voice Gateway provides VoIP connectivity to analog devices, such as analog desk phones, analog conference room phones, fax machines, and modems. Cisco 400 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 ports 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.
- 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)
- FXO failover bypass ports— A failover bypass port, also called a failover trunk bypass, provides a way to use designated analog phone ports to make phone calls through the PSTN during a power outage.
In addition to these features, Cisco 400 Voice Gateway also supports the following features:
- Caller line ID
- G.711, G.729a, and G.726
- G722, iLBC, GSMAMR-NB, and Internet Speech Audio Codec (iSAC)
- 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 is on the roadmap
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
- Support for FXO CAMA signaling type
- Call Detail Record (CDR) information
- Support for interworking with Cisco Unified Communications Manager (Skinny Client Control Protocol [SCCP]), H.323, Session Initiation Protocol (SIP), and Media Gateway Control Protocol (MGCP) 0.1
- Cable detection
- Overload protection
Analog Phone Connectivity
Cisco 400 Voice Gateway are ideal for analog phone deployments ranging from centralized to sparsely concentrated or distributed topologies. Cisco 400 Voice Gateway offer many supplementary analog calling features, depending on the call control and signaling type used. All supplementary analog features are supported through the FXS and FXO ports. The analog interface on Cisco 400 Voice Gateway also supports Feature Access Codes (FACs) for invoking supplementary services.
Fax and Modem Connectivity
FXS ports on Cisco 450 Voice Gateway support fax machines and modems. When using fax machines, the gateways support T.38 fax relay and fax pass-through. T.38 fax relay technologies allow transfer of faxes across the network with high reliability using less bandwidth than a voice call. All modems can be connected to the Cisco VG Series Gateways and are transferred over the network using modem pass-through.
Protocols Supported
The voice gateways support the following protocols:
- SCCP
- H.323v4
- 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
- Cisco Unified Communications Manager or Cisco Unified Communications Manager Express redundancy support using Hot Standby Router Protocol (HSRP)
- Call survivability: MGCP failover to an H.323 connection to the Survivable Remote Site Telephony (SRST) router
- T.38 fax relay and modem pass-through
- Codec support: G.711, G.729. G.729a will be used if the gateway does not support G729 annex b
- RADIUS and TACACS+ for Telnet and authorization