Gateway and Trunk Concepts

Chapter 07

The Process of Converting Voice to Packet

0

Encoding Voice into Binary

mu-law 0 0 1 0 0 1 1 0 is a positive value 1 1 1 0 0 1 0 1 is a negative value

Choosing a Voice Codec

http://www.cisco.com/en/US/prod/collateral/modules/ps3115/ps6024/prod_qas0900aecd8016c6ad_ps3115_Products_Q_and_A_Item.html

RTP and RTCP

– Real-time Transport Protocol• Sequence numbers• Time stamps

• Real-time Transport Control Protocol– Packet count– Packet delay– Packet loss– Jitter (delay variations)

Trunking CME to the PSTN

Trunking CME to Other VoIP Systems

H.323

• The first VoIP

SIP

• Session Initation Protocol– NEXT Generation of H.323

MGCP

• Media Gateway Control Protocol– First true client/server VoIP signaling protocol• “Call agent”

– Not as widely supported as H.323 or SIP

SCCP

• Skinny Client Control Protocol– Only Cisco proprietary protocol in use today– Its function is to provide signaling between the

Cisco Unified Communication Manager and the Cisco IP phones

ITSP (Internet Telephony Service Providers)

• Vonage• Verizon• at&t• Ooma

VoIP ISP in USA (sample list)

• Best• X-Voice• Magic Jack• Nextiva• Avaya• Lingo• Zimbio• NEC• Ooma

• 8x8• Talk Switch• Cisco• ShoreTel• Intalk• Viatalk• VoIP.com• ITP• Vonage

Configuring and Verifying Gateway and Trunk

Chapter 08

Configuring Analog Ports

• FXS• FXO

FXS

Foreign Exchange Station Ports

• Signaling types– Ground start– Loop start

FXO

Foreign Exchange Office

Configuring Digital Voice Ports

• T1 CAS PSTN interfaces• T1 CCS PSTN interfaces

• PBXs use E&M• CAS typically uses loop start

Configuring a T1 CAS PSTN Interface

• Turn to page 253

Configuring a T1 CCS PSTN Interface

• Turn to page 257

Dial Peers (POTS & VoIP Dial Peers)

Voice Call Legs

Configuring POTS Dial Peers

Dial Peer Wildcards

Private Line Automatic Ringdown

• PLAR• FXS PLAR • FXO PLAR

Router Call Processing & Digit Manipulation

Inbound and Outbound Dial Peers

Matching Inbound and Outbound Dial Peers

Failovers & Multiple Voice Paths

Redirecting Operator Calls

Centralizing PSTN Access

Using Translation Profiles

QoS (Quality of Service)

• Bandwidth• Delay– Fixed delay– Variable delay– Jitter (delay variations)– Packet loss

End-to-end delay budget: <150 msJitter: 30 <30 msPacket loss: <1%

Cisco AutoQoS

Advantages over manual QoS configuration• Reduces time of deployment• Provides configuration consistency• Reduces deployment cost• Still allows for manual tuning