2. (VoIP)-Definition
• What is this?
– Voice over Internet Protocol (VoIP) is a general
term for a family of transmission technologies for
delivery of voice communications over the Internet or
other packet-switched networks. Other terms
frequently encountered and synonymous with VoIP
are IP telephony and Internet telephony, as well as
voice over broadband, broadband telephony, and
broadband phone, when the network connectivity is
available over broadband Internet access.
– VoIP systems usually interface with the traditional
public switched telephone network (PSTN) to allow
for transparent phone communications worldwide.
3. VoIP Types
• IP-PBX
-Pure IP to IP endpoints
-Architecture Centralized or Distributed Call
Processing
- “Hosted” IP-PBX applications
• IP-Enabled PBX
– Digital PBX’s with Ethernet Trunk
Cards/Gateways
- Ease of Migration to IP
4. VoIP Architectures
• Centralized
– Call processing, voice mail, and applications are centralized at
one location with transport /access across WAN or public/private
connections
• Call processing can be redundant in this model at two locations for
primary/secondary backup
• Uses more WAN bandwidth due to call switching being centralized
• Distributed
– Call processing is provided at each site
– Voice Mail and applications generally centralized but can also be
distributed
– Increased reliability since each site will function if WAN or carrier
lines fail
– Only uses WAN bandwidth for Intra-WAN calls
5. VoIP Models
• Internal/Standalone
– Isolated school, building, or campus
• WAN Model
– Schools in a district utilize VoIP across the WAN to tie
together their sites, lines also pooled centrally
• IU/Regional Service Center Model
– These centers can tie together individual IU’s, or IU’s
to each district, or County wide centers to each district
• Hosted Services Model
– can tie together various entities thru Carrier based
connections, or the Internet to provide VoIP services
with little or no on-site VoIP equipment
8. VoIP-WAN Model-
Distributed
Server
Voice Mail PSTN
Auto-Attendant
Workgroups CentralizedLines-
PSTN backup PRI
Call Detail Recording
Management
IP
IP Network
Network
Server
PSTN Voice Mail
WIDE Auto-Attendant
IP AREA Workgroups
NETWORK IP Call Detail Recording
Network Management
Network
PSTN
PSTN
IP
Network
PSTN
Distributed Call
Processor Switch(
typ. Each site)
9. VoIP Model-IU/Regional Service
Center
Centralized
All Calls switched thru
PSTN Central Site/All Voice Mail
accessed from Central Site
IP Call Manager-backup
Network Call Manager-primary Server
School District Voice Mail
Auto-Attendant
Workgroups
Call Detail Recording
Management
IP Network
School District
IP Network
PSTN
PSTN
WIDE
AREA
IP
NETWORK
Network Intermediate Unit or
School District
Regional Media Center
PSTN
IP CentralizedLines-
Backup Survivable
Network PSTN backup
PRI
Gateway(typ.) School District
PSTN
Catalyst 3750 SERIES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
1X 11X 13X 23X
SYST
RPS
MASTR
STAT
DUPLX
SPEED
STACK 1 2
MODE 2X 12X 14X 24X
PoE Layer 2/3 Switch(typ)
10. VoIP Model-IU/Regional Service
Center
Distributed
All Calls switched Locally/
All Calls switched thru
PSTN Central Site/All accessed
All Voice Mail Voice Mail
accessed from Central Site
from Central Site
Intra-System Calls
IP between sites and VM
Access and primary
Network calls thru PRI
School District
Server(s)
Voice Mail
VoIP Switch/Call Call Detail Recording
Processor-Local Management
IP Network
School District
IP Network
PSTN
PSTN
WIDE
AREA
IP
NETWORK
Network Intermediate Unit or
School District
Regional Media Center
PSTN
IP CentralizedLines-
Network PSTN backup
PRI-ISDN
PRI
Local Survivable
School District
Gateway(typ.)
VoIP Switch/Call
Processor-Local PSTN
Catalyst 3750 SERIES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
1X 11X 13X 23X
SYST
RPS
MASTR
STAT
DUPLX
SPEED
STACK 1 2
MODE 2X 12X 14X 24X
PoE Layer 2/3 Switch(typ)
11. VoIP Model-IU/Regional Service
Center-Hosted Services
Note handsets are Leased or All Calls switched thru
Call Manager(s)/
provided by the Owner Carrier Site/All Voice Mail
Call Switching
and Services accessed from
Equipment
PSTN Carrier Site
Server(s)
Voice Mail
Auto-Attendant
IP Workgroups
Network Call Detail Recording
School District Management
Other Services
IP Hosted
Carrier Network
PSTN
IP Network Centralized
Lines-PRI/ISDN
School District
IP
PSTN Network
PSTN
WIDE
AREA
IP
NETWORK
Network Intermediate Unit or
911 Calls( Typ.) School District
Regional Media Center
PSAP PSTN
IP
Backup Survivable
Network PSTN backup
Gateway(typ.) School District
PoE and QoS PSTN
reuirements(typ.)
Catalyst 3750 SERIES
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
1X 11X 13X 23X
SYST
RPS
MASTR
STAT
DUPLX
SPEED
STACK 1 2
MODE 2X 12X 14X 24X
PoE Layer 2/3 Switch(typ)
12. Why Implement ?
• “Converge” the Network
– Leverage bandwidth of GIGE or higher networks and
optimize infrastructure
– Eliminate legacy equipment and faulty cabling
systems
– Video over IP and Video Conferencing over IP
– Eliminate physical MAC’s of PBX systems
– Consolidate maintenance contracts under IT
– Consolidate lines and save $$
– Unify Dialing Plans
– Centralized Services to reduce costs
• Intra calls within Regional WAN may remove toll charges
13. Why Implement ?
• Applications that may benefit
– Unification of Voice Messaging with email
– Increased Accessibility of Teachers and Staff
• Find Me/Follow Me
– Phone Directories become electronic
– DID’s provide direct connect calls and direct inward
faxing capabilities
– Caller ID can be provided for ANI, tracing bomb
threats, etc.
– IT technicians and others can roam and be mobile
with “soft” phones and/or WI-FI/cell phones
– Single network to manage
14. Planning
• What voice service/carrier contracts are in place
now?
• Do you want to centralize services?
• What is bandwidth of current WAN’s/LAN’s?
– Do you need an Infrastructure Upgrade?
• What types of network equipment do you have
now?
• Can you implement QoS and/or bandwidth
reservation mechanisms on your WAN’s now?
15. Planning (cont’d)
• Traffic Studies
– Plan capacity of voice traffic across links and compare to network traffic
to assure sufficient bandwidth
– Run Link tests using monitoring software to have baseline of data traffic
• Power Issues
– UPS and/or Generator backup will be required in each closet where
VoIP will be employed
– Cooling of closets may be an issue due to increased heat load
• Equipment Issues
– Network gear needs to support VLANs and QoS or CoS, and Core
switches to support Layer 3( and/or Layer 4 prioritorization)
– Power over Ethernet( PoE) will need to be provided using switches or
mid-span products
• Interfaces
– Public Address, Night Ringers, Cabling to tel. demarcs, number
portability, Faxes, Fax servers/Analog connections
16. Planning (cont’d)
• Do Inventory the network connections, bandwidth, all
network gear, number of phones/phone users, outside
lines/trunks/types, UPS systems, and current telephony
equipment and systems
• Determine if network gear will support QoS/PoE/VLANs
and if it is L2 or L3 or L4
• Do run a VoIP network assessment test from software
or vendor services prior to implementation
• Redundancy-Can you add redundant links or systems in
case of failure or disaster
• Network Security- Protect servers behind Firewalls, use
Voice VLANs to isolate traffic, use VPN’s and/or
encryption over the Internet and/or unsecure links,
physically secure servers..
17. Planning (cont’d)
• Quality of Service( QoS)
– Layer 2 is CoS prioritorization-IEEE 802.1Q( VLAN
tagging) and IEEE 802.1p( 3 bit PCP field)
• IP Precedence using 3 bit PCP field( 8 classes)
• HOW MANY CLASSES DO THE SWITCHES SUPPORT
NOW?( four/port is good, eight/port is best)
• IP Phones typically “stripe” at class 5 for CoS marking in
Layer 2 Ethernet frame
– Layer 3 is DSCP( differentiated services code point)-
DiffServe uses TOS field in the IP field
– Layer 4-can prioritize by UDP port #?
20. Planning (cont’d)
• Network Requirements
– Should use Voice VLANS( by subnet)
– Use DHCP and separate scopes for Voice VLAN
subnets
– Use L2/L3 switches instead of routers
– Use 64K compression G. 711 where possible
– Implement QoS
– Packet Loss less than 1%
– Average Jitter less than 30ms
– One Way Delay no more than 150 ms
– Priority Bandwidth needed per call ~ 106-120kbps
21. Planning-Summary
• Feasibility Study/Assessment
– Survey
– Analysis/Testing
– Options/Costs
– Final Recommendations
– Select next steps for Implementation and pre-
liminary schedule
– Select Vendor here( if possible)
22. Challenges
• Must get a good “picture” of current network (s), and any traffic statistics on
links and WAN links
– Test if possible
• Determine “Physical” impact
– Do you replace switches and routers? (remember PoE impacts)
– Cabling( Cat. 5 min. to the desk)/ connecting backup lines to MDF
– UPS and Power needs for backup
– Locating and backing up central equipment/local equipment
– Are there still analog phones to be connected?
– Must get a good phone count
– Phasing of the Network in cutover
• Determine “Logical” impact
– VLANs/ DHCP scopes/New subnets/Layer 2 and Layer 3/Security
• Additional support/personnel needed from IT to run and maintain the VoIP
on the network
• May not always save $$ by doing VoIP-even if centralizing
• Increase in network complexity by adding voice and “converging”
• Convincing Management to spend the $$
23. Implementation
• Develop Final RFP/RFQ
• Bids and obtain quotes
• Vendor negotiations for material and labor
• Make sure Owner ancilliary equipment provided ahead
of time or in coordination with implementation-UPS’s.
cabinets, cabling, demolition, etc.
• Coordinate IP Addressing Schemes and changes
• Start-ups/Cutovers
• Training very important- can “train the trainer”
• Include MOS (mean opinion score) testing- must have at
least 4.0 or above for toll quality voice per ITU-
P.800/SLA Metric
24. Pitfalls to Avoid
• Do not solely rely on one Vendor
• Don’t overlook the aspects of the physical/logical
infrastructure and the impacts needed to support
VoIP
• Don’t try to oversubscribe the bandwidth and not
implement QoS mechanisms
• Don’t implement without network assessment
testing and running a pilot project for a proposed
manufacturer
• Don’t overlook training of users and additional
support that will be required
25. Costs
• Hard Costs
– typical~ $600 to $800 per IP Phone to implement for VoIP only(
does NOT include data network upgrades)
– Data Network upgrades~ $150 to $300/Ethernet Port( includes
PoE)
• Soft Costs
– Yearly maintenance cost of 15 to 28% /year-varies
– Consultant Fees
• Hidden/Overlooked Costs
– ISDN PRI/DID block monthly costs( e-Ratable) can vary
~$600/mo
– Cost for Voice Traffic studies from current carriers
– Additional Staff needed to maintain/administer new VoIP system
– Mechanical/Electrical upgrades required in closets
– UPS’s, Cabling, Cabinets, Paging Adapters, Misc., etc.
– Servers required to be purchased by Owner
26. Costs-Example
Project Cost Example
Consultant,
$43,000.00 , 5%
Infrastructure, Cisco Data,
$129,135.00 , 14% $332,000.00 , 36%
Cisco VoIP,
$408,447.01 , 45%
Cisco Data Cisco VoIP Infrastructure Consultant
621 IP Phones
28. Lessons Learned
• PLAN,PLAN,PLAN!
• Keep a Contingency in the Budget !
• Decide who is doing what and each responsibility, clear
contracts with the Vendor
• Keep Training Simple for Users and schedule ahead
– Phones
– Voice Mail
– Unified Messaging
• Include all costs to the Owner
• Procure Owner provided equipment in early
• Physically Identify patch panels/ports ahead of time for
any physical cuts, re-patching, reconnections
• Allow for ample time for cutovers-”Murphy” is always
around
