Features and Benefits of Cisco VG450 Voice Gateway
Cisco VG450 Voice Gateway provides VoIP connectivity to analog devices, such as analog desk phones, analog conference room phones, fax machines and modems. Cisco 450 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 SM-X slot on the supported Cisco 4000 Series ISRs without powering off the router.
- 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)
Note |
Switching between the modes requires reload of the ISR chassis. |
- 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 450 Voice Gateway 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 450 Voice Gateway are ideal for analog phone deployments ranging from centralized to sparsely concentrated or distributed topologies. Cisco 4000 Series Integrated Services Routers 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 service modules. The analog interface on Cisco 4000 Series 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
The following table lists the feature specifications for Cisco 450 Voice Gateway.
Feature |
SM-X-8FXS/12FXO |
SM-X-16FXS/2FXO |
SM-X-24FXS/4FXO |
SM-X-72FXS |
---|---|---|---|---|
Tip and Ring Interface for each FXS port |
||||
Interface |
FXS/FXO (RJ-21)RJ-21 ports 0 to 7: FXSRJ-21 ports 8 to 19: FXO |
FXS/FXO (RJ-21)RJ-21 ports 0 to 15: FXSRJ-21 ports 16 and 17: FXO |
FXS (RJ-21), FXO (RJ-11)RJ-21 ports 0 to 23: FXSRJ-11 ports 24 to 27: FXO |
FXS (RJ-21) |
Address signaling format |
In-band DTMF Out-of-band pulse (8 to 12 pps) |
In-band DTMF Out-of-band pulse (8 to 12 pps) |
In-band DTMF Out-of-band pulse (8 to 12 pps) |
In-band DTMF Out-of-band pulse (8 to 12 pps) |
FXS signaling formats |
FXS loop-start, ground-start, and DID signaling |
FXS loop-start, ground-start, and DID signaling |
FXS loop-start, ground-start, and DID signaling |
FXS loop-start, ground-start, and DID signaling |