IP%20telephony%20overview%20and%20demonstration

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IP telephony overview and demonstration

• Prof. Henning Schulzrinne
• (presented by Andrea Forte, Ron Shacham,
• Sangho Shin, Kundan Singh and Xiaotao Wu)
• http//www.cs.columbia.edu/IRT

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Research topics in IRT lab
Internet radio/TV
Internet telephony
Peer-to-peer systems
Quality of service
Security
Internet Real Time
Internet service discovery
Content distribution
VoIP and wireless
Resource reservation
Wireless ad hoc networks
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What is IP telephony?

• Phone call Internet
• User identifier
• Session Initiation Protocol SIP

office.com
alice_at_columbia.edu
Bob
(2)
(1)
pc4.columbia.edu
(3)
home.com
columbia.edu
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Personal mobility
tel[phone]
yahoo.com
alice_95_at_yahoo.com
Home
alice_at_cs.columbia.edu
tel[phone]
Mobile
desk_at_cs.columbia.edu
cs.columbia.edu
Alice.Cueba_at_cs.columbia.edu
host.cs.columbia.edu
Office
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Call setup
Media path
Control path
Office
Forking
Mobile
Visiting university
Redirect
Bob
columbia.edu
Home
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Programmability
Double ringing sound when boss calls
Enter your authentication PIN for billing
Use finger for locating user
B2BUA
Endpoint
Make call when boss is online
Proxy/registrar
Endpoint
Forward to office phone during day, and home
phone during evening

• Common gateway interface (CGI)
• Call processing language (CPL)
• SIP servlet

• Language for End System Services (LESS)

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Clients and servers

• Server
• Proxy, register, redirect.
• Conferencing.
• Voicemail, IVR.

• IP phones

Hardware phones
Urgent
SIP server
Phone
script
Low-priority
Voicemail
Software phones
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Interworking with PSTN
x7040
sipbob_at_cs
(212)5551212
Telephone network (PSTN)
PBX
Telephone subscriber
SIP/PSTN gateway
SIP server
IP endpoint

• Translating
• Audio better codecs on IP
• Signaling some features are lost
• Identifiers phone numbers
• Determining transition points

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Enterprise VoIP
CINEMA servers
Telephone switch
rtspd media server
Local/long distance e.g., 1-212-5551212
sipconf conference server
PSTN
RTSP
RTSP clients e.g., Quicktime
Department PBX
sipum unified messaging
Internal Telephone e.g., 7040
sipd proxy, redirect, registrar
713x
SQL database
cgi
Web based configuration
vxml
SIP/PSTN Gateway e.g., Cisco 2600
7134
7136
siph323 SIP-H.323 translator
H.323
alice_at_cs.columbia.edu (software phone)
H.323 clients e.g., NetMeeting
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VoIP and wireless

• Which wireless network?
• 802.11a/b/g
• Infrastructure mode (security)
• Ad-hoc mode
• What is handoff?
• Handoff happens when a mobile node moves beyond
  the radio range of one access point and enters
  another.

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VoIP and wireless

• What is the problem?
• L2 Handoff time is too big (500 ms) for seamless
  VoIP sessions (90 ms).

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VoIP and wireless

• Improvement in our solution

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Session Mobility

• Focus on communication media audio, video,
  instant messaging
• Location sensors and presence, along with service
  discovery yields a list of local devices
• Seamlessly transfer an active session between
  devices
• Transfer all media to a single device or split
  over multiple devices
• Privacy keep audio on handset, watch video on
  large screen
• Take advantage of benefits of different devices

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Session Mobility
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Serverless (P2P) VoIP

• Server-based
• Cost maintenance, configuration
• Central points of failures
• Controlled infrastructure (e.g., DNS)
• Peer-to-peer
• Robust no central dependency
• Self organizing, no configuration
• Scalability
• P2P-SIP
• Efficient, interoperable, hybrid
• Prototype implementation

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Summary

• SIP-based architecture
• Heterogeneous endpoints
• Telephone, SIP phone, H.323
• Devices like lamp, video encoder
• Multimedia collaboration
• Conference, IM, discussion board, voicemail, file
  sharing
• Advanced services
• Programmable call routing, voice mail,
  interactive voice response
• Fast handoff for WirelessLAN
• P2P-SIP for serverless VoIP

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Conferencing

• Web configuration
• Audio mixing
• Video replication
• SIP, PSTN or H.323

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Voicemail and IVR

• Multi-platform (phone, PC) access
• Standard based (SIP, RTSP)
• Programmable dialogues

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Room conf
Location agent
Device GW
SLinke
Proxy LS
Bob
Trigger an action
X10
sipconf_pingtel for audio
iButton reader
SLP DA
RFID reader
SLP SA
Resource discovery
Tracking
Location-basedServices in our lab
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Location-basedServices in our lab
Room conf
Location agent
Device GW
SLinke
Bob is in conf
Turn on light
Proxy LS
Bob
X10
You are In conf
sipconf_pingtel for audio
Whatsavailable
Turn on confs light
iButton reader
SLP DA
RFID reader
sipconf
SLP SA
Guard communication behavior
Talk to alocation
Location
NOTIFY