Transcript broadband telephony offers

VOIP
(Voice Over Internet Protocol)
CDA 4527
Fall 2006
Definition
– also called IP Telephony, Internet telephony,
Broadband telephony, Broadband Phone and Voice
over Broadband
– the routing of voice conversations over the Internet or
through any other IP-based network
Cisco IP Phone 7941G
Big Picture
• Modes of operation:
–
–
–
–
PC to PC
PC to phone
Phone to PC
Phone to Phone
• Traffic go through Packet
Switched Network instead of
Public Switched Telephone
Network (PSTN)
From Wikipedia, the free encyclopedia
Why VOIP?
• Much cheaper
• Rich functionalities
– Free phone numbers for use with VoIP are available in the USA,
UK and other countries.
– 3-way calling, call forwarding, automatic redial, and caller ID…
– Integrated with data, video communication
• Mobility
– Incoming phone calls can be automatically routed to your VoIP
phone, regardless of where you are connected to the network
Challenges
• Quality of Service (QoS)
– Internet provides best of service
– No guarantee for latency, jitter…
• Need Internet connection
– Home broadband is not reliable
• Power issue
– VOIP phone, Cable Modem/DSL, Computer
Challenges
• Security
– Most unencrypted
– VOIP spam challenges
• Integration into global telephone number
system
• Emergency call availability & functionality
– Power, Internet connection
– Call routing, location service
QoS
• Deal with Jitter
– Smoothed by playback buffer
• Bandwidth
– 64 kbps or less
– Depends on codec and use of silence supression