The Evolution of Gateways

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The Evolution of Gateways Alan Percy AudioCodes
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Evolution
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In the beginning

• Gateways were simple
• MGCP or H.323
• Softswitch had total control
• Little intelligence in the gateway
• G.711 only
• No tone detection
• No Packet Loss Concealment
• Static Jitter Buffers
• And they sounded like it!

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The First Step in Evolution

• Customers wanted more
• Voice Compression
• G.723 and G.729
• Packet Loss Concealment
• Simple Echo Cancellation

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More Steps

• Better performing LBR Coders
• Annexes to G.723 and G.729
• AMR, EVRC and QCELP for wireless
• iLBC for Internet applications
• Advanced Packet Loss Concealment
• Improved Echo cancellation
• 64 and 128 msec echo tails
• Better convergence and performance

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A Big Evolutionary Step

• Gateways Come of Age
• Advanced Call Control - SIP
• OAM
• Command Line
• Embedded SNMP
• Web-based management
• Standard PSTN Protocols
• CAS Signaling
• PRI
• T1, E1 and J1 Physical Interfaces
• Fault Tolerance

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This last year or two

• Important trends that are changing the media
  gateway market

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Trend Designing for Reliability
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Faults and Failures

• Network Failures
• Dropped packets
• Poor throughput
• Interruptions
• Complete Outages
• Equipment Failures
• Failed equipment
• Lightning / Backhoe Induced Interruption
• Power Failures
• Loss of power at site
• Over-temp shutdown

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Designing for Failures Diversity

• Rack and Stack or
• Distribute Equipment
• No one single point of failure
• Spread out load and risk
• Low cost equipment
• SIP Proxy must route around failed equipment

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Designing for Failures Redundancy

• Built-in Redundancy
• 11
• N1
• Automatic Failover
• Hot Swap
• Pros
• Reliability
• Cons
• Complexity

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Proxy Routing

• Proxy detects and routes around failed equipment

INVITE
SIP Proxy
Media Gateways
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Backup Proxy

• Devices are programmed to seek pre-arranged
  backup after loss of communications with primary

Primary Proxy
Proxy, Are you okay?
Media Gateway
Backup Proxy
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Example Distributed Architecture
Primary Proxy
Media Gateways
Backup
Dual Switches
Dual LAN
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PSTN Fall-back

• Gateway Automatically measures network quality
• Redirects calls through backup TDM circuit upon
  failure

SIP
G/W
Network Ok?
T1/E1
Back-up T1/E1
Media Gateway
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PSTN Fall-back Example
WAN
PSTN
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Trend Security

• Applications for Security
• Cable Telephony
• Contact Centers
• Hosted IP-PBX
• Financial Services
• Government

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Points of Risk
Management
Signaling
SIPS
IP
HTTPS
Voice
SRTP
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Trend Media Processing

• Need for Applications to hear network tones
• Live Answer
• No answer
• Busy
• SIT
• Fax
• Answering Machine
• Applications
• Contact Center
• Notification
• IP-PBX

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Trend Blades

• Blade Architecture
• PCI, cPCI
• Advanced TCA
• BladeCenter
• Advantages
• Cost effective
• Greater density
• Easier to manage

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Summary

• A lot has changed in just the last few years
• Protocols and Architectures have evolved (IMS)
• Equipment has evolved too!

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Thanks!