Transcript VoIP, a 10-minute Introduction

VoIP at the University of Oregon
The View from the Telephone Side
Dave Barta, University of Oregon
[email protected]
VoIP Applications
Two Distinct Evaluations
• Voip in the backbone
– OPX replacement
– Tandem networks
• Telephone switching systems to the desktop
OPX Replacement Locations
• Oregon Institute of Marine Biology (OIMB)
– 100 miles from Eugene in Charleston, OR
• Pine Mountain Observatory
– 200 miles east
– Over a major mountain range
– 19 miles from nearest paved road
• Future locations in local area
OPX Replacement - OIMB
• 2 analog ext. off UO PBX - 5 digit dialing
• Trunk group in OIMB key system
– Dial Access Code (DAC) + 5 digits
– Tail End Hop Off (TEHO) in OUS Cities
– LD Access
• Rides US West frame relay T1
– $450/month
– Relatively low traffic
OPX Replacement - OIMB (cont.)
• Replaces one Off Premises Exchange line
(OPX) @$250/month
• No signalling except supervision
• No compression (G.711)
• Quality accptable (but noticeable
difference)
• 2 LEC service areas - GTE, USWest
OPX Replacement - Pine Mountain
• Like OIMB except two phones instead of
key system.
• No OPX before - calls to campus LD. No
access to dedicated LD services.
• Served by T1 frame relay circuit dropped
from microwave tower on same
mountaintop.
OPX Replacement - Local Remotes
• Rate changes creating advantageous climate
– T1 @$300/mo.
– DSL over 4-wire LADs @$48/mo., but
possibly going to $200/mo.
– OPX @$31.50/mo., but possibly going to
$84/mo.
• In use at staff homes
• Contemplated for other off campus offices
VoIP to replace OPX is simple because:
• Usually no DID (although fairly simple
with E&M tie trunk interfaces)
• No need for complex call accounting
• No or simple voicemail requirements
• Simple PBX translations
• Voice bandwidth requirements minimal
VoIP in the OUS Tandem Network
• Challenging
• Interesting
• Cost Effective (probably)
The Oregon University System voice
network connects:
• 3 semi-large universities:
– UO, OSU, PSU
– All in the Willamette Valley
• 4 small regional universities:
– WOU, SOU, EOU, OIT
– Geographically remote
• OHSU - Public corporation in Portland
OUS ETN history and culture
• 1988 - Contract with AT&T
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8 PBXs - Sys 85-G2-G3
Dorm phones for LD resale
Copper and multimode fiber backbones
Voicemail - Audix - Intuity
ETN network and NOC
1992 - H.320 video and MCU
1998 - Y2K upgrades to G3, Intuity, misc. systems
Intelcom Committee sets policy
Equivalent systems across OUS, with exceptions
Funding model subsidizes regional universities
OUS ETN consists of:
• Multiple ISDN-PRI hubbed to OSU
• AT&T SDN long distance from large universities w/ small
schools using OSU SDN
• Video MCU at OSU - multipoint H.320 video or voice and
w/ upgrade H.323 gateway and multipoint
• Shared CMS - ACD and trunking management statistics
• Fault reporting - receives system alarms, filters based on
severity, and pages support staff
• NOC staff
• Call accounting
ETN features:
• 5-digit dialing between campuses - shared # plan
• DCS - passes name info, answer and disconnect
supervision
• SDN access for regional universities
• Networked voicemail - name, # in message header
• TEHO - Tail end hop off in each metro area
• H.320 video between schools and to MCU
• Reliability and stability
Forces of Change:
• Cost Factors
– Long point-to-point T1s to EOU, SOU, OIT
– 384K H.320 video and voice traffic forced T1 #2
• Opportunity factors
– Available OWEN bandwidth in backbone
– SDN rates dropping
– LD market competition
• Technological advances
– Compression
– Features (signalling)
- Reliability
- Standards
ETN Replacement Options:
• ISDN-PRI SDN - Add SDN to regional
schools and use it for LD, TEHO and (with
QSIG) for all ETN functions
• VoIP to some or all schools w/ or w/o
QSIG, depanding on vendor solution
• Hybrid Solution - VoIP in the Valley, ETN
or SDN in the hinterlands
Major Assumption:
All existing features will be
maintained or improved
Challenges
• Bandwidth limited on frame circuits to regional
universities
– At cheap frame price may be worth adding frame
circuits just for voice except…
– US West CIR unreliable
• Support for DCS signaling just emerging
– Cisco to support some sort of signalling soon
– Lucent proprietary solution to packetize signaling
information over IP network whether voice is IP or
ETN
Other Issues
• Call accounting - on-net/off-net pricing based on
PBX trunk group, so not a problem
• Video support
– H.320 much easier with ETN network than SDN or 700
number option for schools without PRI trunking
– Move to H.323 will help but H.320 still growing
• Voice Quality - difference is noticeable, but
meaningful?
Other Issues (cont.)
• Control
– Telecom is sole owner and user of ETN network
(except for AT&T, US West, GTE, and PTI, of course)
– Using OWEN introduces many more interested parties
and we would, for now, be the only isochronous app.
– SOEN/state politics - network ownership is a political
issue which goes outside of higher ed.
• Complexity - more hardware, more protocols,
more people, multiple alarm platforms
Other issues (cont. again)
• Installation cost
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PBX cards
Router ports/cards
Possibly more SDN or frame circuits
Time and energy
• Remote maintenance
– PBXs don’t support IP access for maintenance and
troubleshooting - modem or on-net EIA only
– If/when IP maintenance access, security becomes an
issue
Experimentation
• Cisco solution without signalling
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T1 from PBX to Cisco router at UO and OSU
Discrete trunk group with manual DAC access
QOS available but not necessary
Voice great at G.711, noticeable difference at
G.729(a)
– No fax or modem support
– DID capability
Experimentation (cont.)
• Lucent Internet Telephony Server (ITS)
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Outboard NT Server w/ T1 interface to PBX
DID but no DCS
Good voice, fax support
No compression
Ping and measure delay on call setup and give
busy if too much, but otherwise no QOS
Future Developments
• Cisco to support signaling
– We’re experimenting
• Lucent
– ITS replaced by inboard 3 slot card - G3V7
– 3 slot card replaced by one slot card - G3V8.1
– Support QOS via precedence bit - G3V8.2
VoIP to the Desktop
What we have - What the users want
• Lucent Definity G3 V7 PBX
– 7,000 stations, 550 PSTN trunks,
– 5 T1 to AT&T for SDN, TSAA, 0+
– 3 T1 to ETN network
• Features Supported
– Extensive alarm reporting
– Call coverage off-net and back
– The usual pickup, park, transfer, + 6-way conf.
PBX features (cont.)
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ACD call centers w/ realtime, summary reports
Integrated and networked voicemail
Multiple sets from POTS to 36-button display
Supports wireless integration
Caller ID (# only) on digital sets and analog
(v8.2)
– Legacy applications - alarms, modems, faxes,
emergency phones, elevator phones
– ISDN-BRI
Experimenting with IP Phones
• Purchased Selsius Trial Pack
– 6 sets used consistently on campus
– Sets to remote locations
• One at OSU via Owen - worked fine
• Took one to SLCC and used over congested
commodity internet - that was cool and useful
• OSU to try same trick with telecommuter in Phoenix
- a potentially useful application.
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Simple programming interface
Limited feature set
Lots of IP PBX rebooting
g.723(1) did not pass muster
Issues/obstacles to real implementation
• Full feature set, array of telephone sets, and set
cost
• Redundancy/reliability in controllers and core
routers
• Distributed architecture means distributed backup
power - $ and space
• e911 - solvable at the expense of mobility
• Voice quality - compressed voice IS different, but
does it matter?
My opinion
• Seriously viable in small locations
– Reduced feature requirements
– Consolidated closets so power not an issue
– Usually not fully integrated with campus
voicemail, etc. so not an issue
– Price will decide
• Soon a good option on a campus without an
existing cable plant
Last few opinions
• Wouldn’t want to be facing a PBX decision right
now - cutting a large PBX is hard enough without
it being a beta test
• PSTN response important
– IP or some packet approach would reduce expensive
SONET gear
– It’s time for compression
– IP to PSTN breaks their pricing model to our advantage
• Hybrid of traditional telephony, IP, wireless