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Cisco VG 224 Analog Phone Gateway

The Cisco® VG 224 Analog Phone Gateway enables an IP telephony solution to continue using traditional analog devices while taking advantage of the productivity afforded by IP infrastructure.

The Cisco Unified Communications system of voice and IP communications products and applications enables organizations to communicate more effectively-helping them to streamline business processes, reach the right resource the first time, and impact the top and bottom line. The Cisco Unified Communications portfolio is a key part of the Cisco Business Communications Solution-an integrated solution for organizations of all sizes which also includes network infrastructure, security, and network management products, wireless connectivity, and a lifecycle services approach, along with flexible deployment and outsourced management options, end-user and partner financing packages, and third-party communications applications.

Figure 1. Cisco VG 224 Analog Phone Gateway

The Cisco VG 224 (Figure 1) is a Cisco IOS® Software-based high-density 24-port gateway for analog phones, fax machines, modems, and speakerphones within an enterprise voice system based on Cisco Unified CallManager. Having these devices tightly integrated with the IP-based phone system is advantageous for increased manageability, scalability, and cost-effectiveness (Figure 2). Commercial businesses can also use the Cisco VG 224 with Cisco Unified CallManager Express to effectively augment an integrated services router (ISR) environment. Either topology environment will support business needs for a high concentration of analog voice ports for modem calls, fax calls, and analog supplementary services (Figure 3).

The Cisco VG 224 offers Cisco IOS Software manageability with 24 analog phone lines to be used as extensions to the Cisco Unified CallManager or Cisco Unified CallManager Express system in a very compact 19-inch rack-mount chassis.


  • Cisco IOS Software-Based Hardware-The hardware includes uniform Cisco command-line interface (CLI) and Simple Network Management Protocol version 3 (SNMPv3) support for ease of gateway configuration and operation.
  • Robust Voice Quality-Cisco experience in providing toll-quality packet-voice service helps ensure that the Cisco VG 224 provides the clear, robust voice quality end users have come to expect from telephony services.
  • Investment Protection-Customers can continue to use existing analog phones, fax machines, and modems while taking advantage of IP telephony. Basic analog phone connectivity is needed when the infrastructure (wiring) or application does not support or require IP phones. The Cisco VG 224 is the ideal platform to support analog phone lines, allowing organizations to deploy IP telephony without having to purchase IP phones for all users and to continue using existing devices. Cisco VG 224 can also be used in a Cisco Unified CallManager Express environment and migrated to Cisco Unified CallManager deployment with 100 percent investment protection.
  • High Availability-Customers will experience less voice downtime due to WAN link failure. Cisco VG 224 has built-in Media Gateway Control Protocol (MGCP) failover to an H.323 connection to a Survivable Remote Site Telephony (SRST) router. This failover will maintain voice service for analog endpoints in the event of WAN link failure and lost connectivity to the Cisco Unified CallManager. Cisco VG 224 also can use a 12V DC UPS for up to 8 hours of battery backup.
  • Reduced Barrier to Entry-This provides a low-cost alternative for low-end analog phones and allows organizations to take advantage of IP telephony with a lower overall IP telephony investment.

Figure 2. Cisco VG 224 Integration with Cisco Unified CallManager

Figure 3. Cisco VG 224 Integration with Cisco Unified CallManager Express


The Cisco VG 224 is ideal for implementations in which analog phones are needed. The VG 224 provides a high level of availability at locations with MGCP Fallback, with ease of manageability using Cisco IOS Software monitoring features. Cisco VG 224 offers many supplementary analog calling features depending on the call control and signaling type used. Refer to Table 1 for the supplementary analog calling features available.

Table 1. Analog Supplementary Features available on Cisco VG224

  H.323 Features With Cisco Unified CallManager Express MGCP Features With Cisco Unified CallManager Express SCCP Features With Cisco Unified CallManager SCCP Features With Cisco Unified CallManager Express SIP Features With Cisco Unified CallManager Express
Basic Call X X X X X
Call Forward All     X X  
Call Forward Busy     X X  
Call Forward Cancel     X X  
Call Forward No Answer     X X  
Call Hold X   X X X
Call Pickup Group     X X  
Call Pickup Local     X X  
Call Transfer Blind X   X X X
Call Transfer Consultative     X X X
Call Waiting     X X  
Caller ID X X X X X
Conference Call     Up to 3 parties Up to 3 parties  
Directed Call Park       X  
Directed Call Pickup       X  
Directed Call Pickup of Ringing Extension       X  
Redial     X X  
Speed Dial     X X  


The Cisco VG 224 supports fax machines and modems. When using fax machines, the Cisco VG 224 supports Cisco fax relay, T.38 fax relay, and fax passthrough. Cisco or 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 224 and will be transferred over the network using modem passthrough.


  • SCCP
  • H.323v4
  • MGCP
  • SIP
  • Real-Time Transport Protocol (RTP)
  • Secure Real-Time Transport Protocol (SRTP)
  • Trivial File Transfer Protocol (TFTP)
  • HTTP server
  • SNMP
  • Telnet
  • Dynamic Host Configuration Protocol (DHCP)
  • Domain Name System (DNS)
  • Cisco Unified CallManager 3.3.3 SR2 or higher version
  • Cisco Unified CallManager Express 4.3.2 or higher version
  • Cisco Unified CallManager or Cisco Unified CallManager Express redundancy support using Hot Standby Router Protocol (HSRP)
  • Call survivability-MGCP failover to an H.323 connection to the SRST router
  • Cisco fax relay, T.38 fax relay, and modem pass-through
  • Coder/decoder (codec) support, G.711, G.729a
  • RADIUS and TACACS+ for Telnet and authorization



  • Processor: RISC processor
  • Memory (default): 128 MB SDRAM
  • Compact Flash: One slot Type II
  • Ethernet: Two 10/100BASE-T Ethernet ports
  • Console/auxiliary (max): Up to 119.2 kbps per port


  • AC Input Voltage: 100 to 240 VAC
  • AC Input Current (max): 1 Amp
  • DC Input Voltage: 12V
  • Frequency: 50 to 60 Hz
  • Power Dissipation: 60W


  • Width: 444.5 mm)
  • Height: 44.4 mm) (add 0.17 inch for optional rubber feet)
  • Depth: 342.9 mm)
  • Weight (max): 4.106 kg)
  • Rack and wall mountable

Table 2. Voice Port

Category Specification
Tip/Ring Interfaces for Each FXS Port (SLIC)
Ring Voltage 50V if no DC offset
Ring Frequency 20, 25, 30, 50 Hz
Ring Waveform Sine wave if no DC offset20V and 24V DC offset will be trapezoidal
Ring Load 1400 ohm + 40µF(Up to three ports at one time)
Loop Resistance Up to 600 ohm (including the phone or terminal equipment)
On-Hook/Off-Hook Characteristics -
Off-Hook Current 25 mA (maximum)
RJ-11 FXS Port Terminating Impedance Option 600 ohm complex, 600 ohm real, 900 ohm complex, 900 ohm real, complex1, and complex2


  • Operating temperature: 0 to 50ºC)
  • Nonoperating temperature: -40 to 85ºC)
  • Operating humidity: 5 to 95% noncondensing
  • Noise level (max): 38-dbA @ 0.914 meters)
  • On premise only, restricted access area, permanent ground required, to be installed and serviced only by trained professionals

This equipment complies with all the regulatory requirements for connection to the communications networks of each country in which it is sold.


To order this product, use the following information:

Product Number: VG 224

Product Description: Cisco VG 224 Analog Phone Gateway