The document provides an overview of the Session Initiation Protocol (SIP), detailing its capabilities, components, and functioning within a network. It explains the roles of user agents, proxy servers, and redirect servers, as well as how to perform basic SIP configuration. Additionally, it outlines specific commands for SIP bind features and configuring call transfer and registration for Cisco IOS gateways.

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& www.uccollaborations.com

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CCNP Voice Plus Overview
Voice Gateways & Signaling
Protocol.
SIP IOS Gateway

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Overview
• Session Initiation Protocol (SIP) is an ASCII-based
• Application-layer control protocol that can be used to establish, maintain, and
terminate calls between two or more endpoints
• SIP is a peer-to-peer protocol
• SIP provides the following capabilities
–Determines the location of the target endpoint
–Determines the media capabilities of the target endpoint
–Determines the availability of the target endpoint
–Establishes a session between the originating and target endpoints
–Handles the transfer and termination of calls
• Users in a SIP network are identified by unique SIP addresses
• A SIP address is similar to an e-mail address and is in the format of
sip:fkhan@uccollaborations.com

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SIP Components
• The peers in a session are called user agents (UAs)
–User-agent client (UAC)—A client application that initiates the
SIP request
–User-agent server (UAS)—A server application that contacts the
user when a SIP request is received and that returns a response on
behalf of the user
• SIP endpoint is capable of functioning as both a UAC and
a UAS but functions only as one or the other per
transaction

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SIP Clients
• Phones—Can act as either UAS or UAC
–Softphones
–Ephone (such as hardware phone)
• Gateways

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SIP Servers
• Proxy server
–Receives SIP requests from a client and forwards them on the
client's behalf
–Provide call routing
–Authentication, authorization, network access control
• Redirect server
–Provides the client with information about the next hop or hops
that a message should take and then the client contacts the next-
hop server or UAS directly
• Registrar server
–Processes requests from UACs for registration of their current
location

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How SIP Works with a Proxy Server
• Caller UA sends an INVITE request to the proxy server and then the proxy server determines the
path and forwards the request to the called party
• The called UA responds to the proxy server, which then forwards the response to the caller
Request
Response

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How SIP Works with a Redirect
Server
• Caller UA sends a SIP INVITE request to the redirect server
• Redirect contacts the location server to determine the path to the called party
and sends that information back to the caller UA
• The caller UA then sends a SIP INVITE request directly to the device
indicated in the redirect information

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Perform Basic SIP Configuration
• How to Configure SIP Bind Features
–SIP signaling and media paths can advertise the same source IP
address on the gateway for certain applications
–the bind command adds flexibility by assigning a gateway to a
specific interface (and therefore the associated address) for the
signaling or media application
–You can obtain a predefined and separate interface for both
signaling and media traffic
–the bind command allows you to configure the source IP address
of signaling and media packets to a specific interface's IP address

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Enabling Blind Command
• Global Command
voice service voip
Sip
Bind all source-interface loopback 0
• Dial Peer Level
dial-peer voice 1 voip
session protocol sipv2
voice-class sip bind control source-interface Loopback0
voice-class sip bind media source-interface Loopback0

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Configuring SIP Call Transfer Using
the Refer Method
dial-peer voice 3001 voip
application session
incoming called-number 1408T
destination-pattern 1408T
session protocol sipv2
session target ipv4:172.16.25.21
codec g711ulaw
!
dial-peer voice 3002 pots
application session
destination-pattern 9[2-9]…..
direct-inward-dial
port 2/0:0
!
sip-ua
retry bye 1
retry refer 3
timers notify 400
timers refer 567
no oli
sip-server ipv4:172.16.21.21  SIP Proxy Server
voice service voip
sip
bind control source-interface Loopback0
bind media source-interface Loopback0
!

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Configure Gateway to register to SIP
Proxy Server
• To register a Cisco IOS Gateway using username/password
sip-ua
credentials username fkhan password 7 030752180500 realm voicebootcamp.com
registrar ipv4:172.16.21.21 expires 3600
sip-server ipv4:172.16.21.21
!
dial-peer voice 1 voip
destination-pattern 011T
voice-class codec 1
voice-class sip dtmf-relay force rtp-nte
session protocol sipv2
session target sip-server
incoming called-number .%
dtmf-relay rtp-nte
no vad
voice service voip
redirect ip2ip
sip
bind control source-interface Loopback0
bind media source-interface Loopback0
registrar server expires max 3600 min 3600
!

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Configure Cisco IP Gateway using
IP Address
dial-peer voice 1 voip
destination-pattern 011T
voice-class codec 1
voice-class sip dtmf-relay force rtp-nte
session protocol sipv2
session target ipv4:142.11.64.21
incoming called-number .%
dtmf-relay rtp-nte
no vad
voice service voip
redirect ip2ip
sip
bind control source-interface Loopback0
bind media source-interface Loopback0
registrar server expires max 3600 min 3600
!

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The End