VoIP Technology Developments
Net@EDU
Co-leaders: José A. Domínguez (University of Oregon)
http://ns.uoregon.edu/~jad/Net@EDU/
Several Uses for VoIP
• Voice Trunk Replacement
• End-user Appliances
• Computer Telephony & VoIP
Elements of the Current Technology
• Switching Devices (unPBX/IP PBX)
• End-user Devices (IP Telephones, Ethernet Telephones, Computer Telephony Apps, Regular Analog/Digital Telephones)
• Access Gateways (Analog/Digital)
• Wireless VoIP
VoIP Technology (CODECs)
• G.711 (PCM) – 64Kbps (4.4 MOS)• G.721, G.723, G.726 (ADPCM) – 16, 24,
32, 40 Kbps (4.2 MOS)• G.728 (LD-CELP) – 16 Kbps (4.2 MOS)• G.729, G.729a (CS-ACELP) – 8Kbps (4.2
MOS)• G.723.1 (CS-ACELP) – 5.3Kbps (3.5
MOS), 6.3Kbps (3.98 MOS)
VoIP Technology (Delays)
• Fixed Delay Components:– Propagation Delay– Serialization Delay– Processing Delay
• Variable Delays:– Queuing Delay
VoIP Technology (Call Setup)
• H.323 Standard (Video conferencing over Packet/Data Networks)– H.225
– H.245
• Real-Time Transport Protocol (RTP)/Real-Time Transport Control Protocol (RTCP)
• Session Initiation Protocol (SIP)• Multimedia Gateway Control Protocol (MGCP)
VoIP Technology (QoS)
• Dejitter Buffer
• Type of Service (TOS)
• Weighted Fair Queuing (WFQ)
• Random Early Detection (RED)
• Weighted RED (WRED)
• Multilink PPP (MLPPP)
• Resource Reservation Protocol (RSVP)
Concerns To Be Addressed
• Powering for End-user Devices
• Reliability
• Troubleshooting VoIP Services
• Access to Emergency Services and related issues (Liability)
What has changed?
• IP Telephones powered by proprietary switching devices
• Converters for Current devices
• Some more layers of reliability have been added
• New services added to IP PBXs and gateways
Things that we are still missing
• Device location. Similar to cell phone triangulation. How about GPS?
• Standardization for power provisioning
• Plan for an open environment similar to the current data and voice networks
• Management platforms
UO VoIP Services
• Equipment:– Redundant IP/PBX Call Manager– Cisco Digital/Analog Gateways– Cisco’s IP Telephones
• Services Offered:– VoIP Trunks to Remote Sites– On Campus Mobility via IP Telephones
Tracking Technology Changes
• Mailing Lists– IETF’s IP Telephony WG ([email protected])– IETF’s PSTN & Internet Internetworking WG (
[email protected])– IETF’s Media Gateway Control WG (
[email protected])– Session Initiation Protocol WG (
[email protected])– Other IETF WGs (SPIRITS, ENUM, RSVP, DIFFSERV,
AVT, INTSERV)– Computer Telephony Newsletter (
Tracking Technology Changes
• Websites– Internet Technical Resources
(http://www.cs.columbia.edu/~hgs/internet)– Hello Direct (http://www.phonezone.com)– Internet Telephony (
http://www.fokus.gmd.de/research/cc/glone/projects/ipt)– Computer Telephony (http://www.telecomlibrary.com)– European Telecommunications Standards Institute
(http://www.etsi.org/tiphon)– Internet & Telecomms Convergence Consortium
(http://itel.mit.edu)
Tracking Technology Changes
• Hardware Manufacturers– Cisco Systems (http://www.cisco.com)– Lucent Technologies (http://www.lucent.com)– 3Com (http://www.3com.com)– Nortel Networks
(http://www.nortelnetworks.com)– Vocaltec (http://www.vocaltec.com)– RadVision (http://www.radvision.com)
Books in the market
• IP Telephony (Bill Douskalis)
• Voice over IP (???)
• Voice over Data Networks (???)
Recommended
