01 - Adapting Legacy Phone Systems to Voip
Transcript of 01 - Adapting Legacy Phone Systems to Voip
www.convergencetechnologycenter.org DUE 402356
Adapting Legacy Phone Systems to VoIP
Vincente D’IngianniDirector of Professional ServicesBinary Systems, [email protected]
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What We’ll Cover… What’s inside the PSTN? What’s inside the IP network? VoIP gateways Connecting the IP network to the PSTN Bandwidth Remote PSTN users – “The Old Way” Remote VoIP users – “The New Way” Remote PSTN locations – “The Old Way” Remote VoIP locations – “The New Way” Do I need a Softswitch? Do I need a VoIP carrier?
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The Legacy PSTN
Public Switched Telephone Network
Enterprise Network
PSTN
Enterprise Network Subscribers
Subscribers
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What’s Inside the PSTN?
Class 4 Tandem Switch
Class 5 End Office Switch
Enterprise Network
Subscribers
Subscribers
Enterprise Network
Public Switched Telephone Network
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Forgetting the Complexity
Public Switched Telephone Network
Enterprise Network
PSTN
Enterprise Network Subscribers
Subscribers
All Routing Logic is managed by theService Provider’s Network – Not yours.
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What We’ll Cover… What’s inside the PSTN? What’s inside the IP network? VoIP gateways Connecting the IP network to the PSTN Bandwidth Remote PSTN users – “The Old Way” Remote VoIP users – “The New Way” Remote PSTN locations – “The Old Way” Remote VoIP locations – “The New Way” Do I need a Softswitch? Do I need a VoIP carrier?
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Enter the IP Network
Enterprise Network
PSTN
Enterprise Network Subscribers
Subscribers
IP Network
Public Internet or Private WAN
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Focusing on VoIP
Enterprise Network
Enterprise Network Subscribers
Subscribers
IP Network
Public Internet or Private WAN
VoIP gives you the option to take control of your Communication
Network
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What’s Inside an IP Network?
Enterprise Network
Enterprise Network Subscribers
Subscribers
Public Internet or Private WAN
Firewall
Firewall
Routers
Routers
Routers
In most cases, IP Routing Logic is still managed by a Service
Provider’s Network – Not yours
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Forgetting the Complexity
Enterprise Network
Enterprise Network Subscribers
Subscribers
IP Network
Public Internet or Private WAN
VoIP Communication Protocols, such as SIP & H.323, allow control of your communication routing without interfering with the Service Providers
Network
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What We’ll Cover… What’s inside the PSTN? What’s inside the IP network? VoIP gateways Connecting the IP network to the PSTN Bandwidth Remote PSTN users – “The Old Way” Remote VoIP users – “The New Way” Remote PSTN locations – “The Old Way” Remote VoIP locations – “The New Way” Do I need a Softswitch? Do I need a VoIP carrier?
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Fax-Demodulation- Handshaking
SignalingInterworking
VoIP<-> PSTN
IPProcessing
-IP- TCP- UDP- RTP
PSTN
PBX
EthernetPPP
Frame RelayATM
IP Voice
Applications/ManagementProcessing
SignalingInterworking
VoIP <-> PSTN
Fax– Demodulation– Handshaking
Voice-Compression- Echo Cancellation-Silence Suppression
PSTNPorts
-AnalogC.O
-T1/E1IP Network
VoIP Media Gateways provide the bridge between Legacy Phone
Systems and VoIP
What are VoIP Media Gateways?
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PSTN
PBX
EthernetPPP
Frame RelayATM
IP Voice
IP Network
Vega 50Analog VoIP Gateway
• Analog Ports for FXS or FXO Signaling• Supports PSTN/PBX or Telephone Lines• Connection to the IP Network Via 100Base-T Ethernet Interface• SIP, H.323• Selectable Coders Per Channel: G.711, G.723, G.729• T.38 Fax Relay
Analog VoIP Gateways
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PSTN
PBX
EthernetPPP
Frame RelayATM
IP Voice
IP Network
Digital Trunking VoIP Gateways
Vega 400Trunking VoIP Gateway
• Supports PSTN/PBX Digital Trunks• T1 / E1 ISDN, North American CAS, R2• Connection to the IP Network Via 100Base-T Ethernet Interface• SIP, H.323• Selectable Coders Per Channel: G.711, G.723, G.729• T.38 Fax Relay
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What We’ll Cover… What’s inside the PSTN? What’s inside the IP network? VoIP gateways Connecting the IP network to the PSTN Bandwidth Remote PSTN users – “The Old Way” Remote VoIP users – “The New Way” Remote PSTN locations – “The Old Way” Remote VoIP locations – “The New Way” Do I need a Softswitch? Do I need a VoIP carrier?
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Bridging the Networks
PSTN
IP Network
VegaStreamTrunking VoIP Gateway
VegaStreamAnalog VoIP Gateway
EthernetEthernet
DigitalTrunks
FXOLines
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Bridging the Networks (cont.)
Firewall
Firewall
Routers
Routers
Routers
IP Network
EthernetEthernet
VegaStreamTrunking VoIP Gateway
VegaStreamAnalog VoIP Gateway
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Bridging the Networks (cont.)
PSTN
Class 4 Tandem Switch
Class 5 End Office Switch
FXOLinesDigital
TrunksVegaStreamTrunking VoIP Gateway
VegaStreamAnalog VoIP Gateway
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PSTN
IP NetworkEthernet
Ethernet
User SideDigitalTrunks
Enterprise Network
Private Extensions
FXSLines
Network SideDigitalTrunks
FXOLines
VegaStreamTrunking VoIP Gateway
VegaStreamAnalog VoIP Gateway
Bridging Public and Private Networks
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The “Leaky” PBX
PSTN
IP NetworkEthernetEthernet
Enterprise Network
Network SideDigitalTrunks
FXOLines
Enterprise Network
Using Legacy PBX Routing functionality, users may dial a prefix to bypass the PSTN Calls are routed via VoIP to remote locations/countries Standard PSTN Toll charges are bypassed “Enterprising Enterprises” resell the ability to terminate calls on their local PSTN connection so other VoIP
users can benefit (not necessarily legal)
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What We’ll Cover… What’s inside the PSTN? What’s inside the IP network? VoIP gateways Connecting the IP network to the PSTN Bandwidth Remote PSTN users – “The Old Way” Remote VoIP users – “The New Way” Remote PSTN locations – “The Old Way” Remote VoIP locations – “The New Way” Do I need a Softswitch? Do I need a VoIP carrier?
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PSTN
IP NetworkEthernetEthernet
Enterprise Network
Network SideDigitalTrunks
FXOLines
Enterprise Network
Calculate the number of calls that you will be making simultaneously over your IP connection Estimate approximately 80-90 kbps uncompressed per call A T3 (28 T1s) of voice will fill a 100 Mb Ethernet link
Bandwidth Requirements
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Most cable modems provide asymmetrical bandwidth 3 Mb downstream is popular 256K upstream is typical
Don’t expect to force an entire trunk worth of voice through a cable modem or DSL
Vega 400 TrunkingVoIP Gateway
E1 PRI
CableModem
256KUpstream
Bandwidth Requirements
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What We’ll Cover… What’s inside the PSTN? What’s inside the IP network? VoIP gateways Connecting the IP network to the PSTN Bandwidth Remote PSTN users – “The Old Way” Remote VoIP users – “The New Way” Remote PSTN locations – “The Old Way” Remote VoIP locations – “The New Way” Do I need a Softswitch? Do I need a VoIP carrier?
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PBX/CO
The Switch provides the “Talk Battery” to power a phone The switch provides the dial tone The phone generates the digits
POTS Line
POTS Line connected to a PBX/CO
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Foreign Exchange Office (FXO) Emulates a telephone set connects to a standard line side interface of the PBX or central office
PrivateNetwork
PBX/CO FXO
Foreign Exchange Office (FXO)
This is the way that Interexchange carriers were forced to connect with AT&T before equal access Carriers would purchase simple lines in each city to create a POP These lines were directly connected into their switching networks Subscribers dialed 7-digit access numbers to receive dial tone from the carrier
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Foreign Exchange Station (FXS) Emulates a switch port connects to a standard telephone line Signaling can be loop start or ground start
PrivateNetwork
FXS
Foreign Exchange Station (FXS)
POTS Line
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Foreign Exchange Office (FXO) Emulates a telephone set connects to a standard line side interface of the PBX/CO
Foreign Exchange Station (FXS) Emulates a switch port connects to a standard telephone line Signaling can be loop start or ground start
PrivateNetwork
PBX/CO FXO FXS
Combination of FXO/FXS allows a remote station to appear as a standard line:
POTS Line
Extensions use a combination of FXO and FXS
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What We’ll Cover… What’s inside the PSTN? What’s inside the IP network? VoIP gateways Connecting the IP network to the PSTN Bandwidth Remote PSTN users – “The Old Way” Remote VoIP users – “The New Way” Remote PSTN locations – “The Old Way” Remote VoIP locations – “The New Way” Do I need a Softswitch? Do I need a VoIP carrier?
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Public Switched Telephone Network
Enterprise Network
PSTN
Enterprise Network Subscribers
Subscribers
Remote VoIP Users
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PSTN
SubscribersEnterprise Network
Remote Lines
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PSTN
SubscribersEnterprise Network
IP Network
Public Internet or Private WAN
Cable Modems or DSL can be used for low numbers of remote users.
Adding a VoIP Network
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Public Internet or Private WAN
Vega 50Analog FXO
VoIP Gateway
Vega 50Analog FXS
VoIP Gateway
PSTN
SubscribersEnterprise Network
IP Network
Adding VoIP Gateways
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Public Internet or Private WAN
PSTN
IP Network
SubscribersEnterprise Network
Vega 50Analog FXO
VoIP Gateway
Vega 50Analog FXS
VoIP Gateway
Bypassing the PSTN
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Public Internet or Private WAN
IP Network
SubscribersEnterprise Network
Call routing between VoIP Gateways is configured locally.
Vega 50Analog FXO
VoIP Gateway
Vega 50Analog FXS
VoIP Gateway
Remote User Connected via VoIP
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Analog FXOVoIP Gateway192.168.1.123
Enterprise Network
Configuring Local FXO Extensions
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Analog FXOVoIP Gateway192.168.1.123
Enterprise Network
Configuring Local FXO Routing
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Analog FXSVoIP Gateway192.168.1.202
Subscribers
Configuring Remote FXS Extensions
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Analog FXSVoIP Gateway192.168.1.202
Subscribers
Configuring Remote FXS Routing
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Public Internet or Private WAN
IP Network
SubscribersEnterprise Network
Subscribers maintain all feature functionality as local users on the
PBX.
Vega 50Analog FXO
VoIP Gateway
Vega 50Analog FXS
VoIP Gateway
Remote Users connected via VoIP
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IP Network
SubscribersEnterprise NetworkIP Phones
An IP phone is simply a single-port VoIP media gateway
Vega 50Analog FXO
VoIP Gateway
Vega 50Analog FXS
VoIP Gateway
Adding IP-Only Users
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What We’ll Cover… What’s inside the PSTN? What’s inside the IP network? VoIP gateways Connecting the IP network to the PSTN Bandwidth Remote PSTN users – “The Old Way” Remote VoIP users – “The New Way” Remote PSTN locations – “The Old Way” Remote VoIP locations – “The New Way” Do I need a Softswitch? Do I need a VoIP carrier?
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In-Band Signaling CAS – Channel Associated Signaling R2 E&M Wink Start FGD
D-Channel
Trunk Signaling Methods
Out-of-Band Signaling ISDN / Q.931 SS7
Bearer Channel
Combined Voice and Signaling Channel
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D-Channel
Network vs. User Side ISDN
Network side ISDN Network side ISDN provides a standard PRI interface to a
PBX and mimics the behavior of legacy phone switches User Side ISDN
User side ISDN provides a standard ISDN PRI interface to the Public Switched Telephone Network (PSTN)
Bearer Channel
PSTN
Network Side
User Side
Clock Timing
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What We’ll Cover… What’s inside the PSTN? What’s inside the IP network? VoIP gateways Connecting the IP network to the PSTN Bandwidth Remote PSTN users – “The Old Way” Remote VoIP users – “The New Way” Remote PSTN locations – “The Old Way” Remote VoIP locations – “The New Way” Do I need a Softswitch? Do I need a VoIP carrier?
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Public Switched Telephone Network
Enterprise Network
PSTN
Enterprise Network Subscribers
Subscribers
Remote VoIP Locations – PSTN Connectivity
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PSTN
Enterprise Network
Enterprise Network
Network Side
User Side
User Side
ISDN PRI
ISDN PRI
Remote VoIP Locations – Connecting Locations via PSTN
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IP Network
PSTN
Enterprise Network
Enterprise Network
Remote VoIP Locations - Adding VoIP
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PSTN
Enterprise Network
Enterprise Network
IP Network
Remote VoIP Locations – Adding VoIP
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PSTN
IP Network
Enterprise Network
Enterprise Network
Network Side
Network Side
User Side
User Side
ISDN PRI
ISDN PRI
Vega 400PRI VoIP Gateway
Vega 400PRI VoIP Gateway
Remote VoIP Locations – Adding VoIP Gateways
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IP Network
Enterprise Network
Enterprise Network
Network Side
Network Side
User Side
User Side
ISDN PRI
ISDN PRI
Vega 400PRI VoIP Gateway
Vega 400PRI VoIP Gateway
Remote VoIP Locations – PSTN Bypass
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IP Network
Enterprise Network
Enterprise Network
IP Phones
Vega 400PRI VoIP Gateway
Vega 400PRI VoIP Gateway
Remote VoIP Locations – Adding IP-Only Users
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What We’ll Cover… What’s inside the PSTN? What’s inside the IP network? VoIP gateways Connecting the IP network to the PSTN Bandwidth Remote PSTN users – “The Old Way” Remote VoIP users – “The New Way” Remote PSTN locations – “The Old Way” Remote VoIP locations – “The New Way” Do I need a Softswitch? Do I need a VoIP carrier?
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Do I Need a Softswitch?
Ask these questions: Does your existing PBX have the features that you
need? What VoIP control protocols do your
gateways/endpoints support? How many VoIP gateways/endpoints do you need?
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Remote VoIP users can transparently utilize features from the legacy PBX/switch Virtual Private Networks for Voice can be
created via existing PBX Routing Tables Features such as T.38 Fax Relay and RFC 2833
digit transport provide reliable communication over low bandwidth connections
Does Your Existing PBX Have the Features That You Need?
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MGCP and MEGACO are Master-Slave protocols MGCP and MEGACO require a Call Agent/Softswitch to instruct the
Endpoint to perform all functionality If communication with the Call Agent is lost, the endpoint cannot
function These protocols require a Softswitch
SIP and H.323 are peer-to-peer protocols SIP and H.323 gateways offer internal routing tables and features
that often rival the legacy PBX or Key System itself If communication with the Proxy/Gatekeeper/Softswitch is lost,
internal routing tables may be used. For example, “911”
SIP is continually evolving to support next generation features
What VoIP Control Protocols do Gateways Support?
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Softswitches, SIP proxies, and H.323 gatekeepers provide a single point of configuration for advanced network features
IP Network
Enterprise Network
Enterprise Network
IP PhoneIP Phone
SoftswitchFeature Server
Vega 400Trunking VoIP Gateway
Vega 400Trunking VoIP Gateway
How Many VoIP Endpoints Do You Have?
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What We’ll Cover… What’s inside the PSTN? What’s inside the IP network? VoIP gateways Connecting the IP network to the PSTN Bandwidth Remote PSTN users – “The Old Way” Remote VoIP users – “The New Way” Remote PSTN locations – “The Old Way” Remote VoIP locations – “The New Way” Do I need a Softswitch? Do I need a VoIP carrier?
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PSTN
IP NetworkEthernetEthernet
Enterprise Network
Network SideDigitalTrunks
FXOLines
Enterprise Network
VoIP Carriers provide alternate IP-based call routing to remote endpoints via the public Internet Calls are routed via VoIP to remote locations/countries and standard PSTN Toll charges are
bypassed
VoIP Carrier’sSoftswitch / Feature Server
Do I Need a VoIP Carrier?
Vega 400Trunking VoIP Gateway
Vega 50Analog VoIP Gateway
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Can I Cut the Cord to the PSTN?
IP NetworkEthernet
Enterprise Network Enterprise Network
If you are satisfied with the reliability of your high-speed internet provider and VoIP carrier’s feature set and destination choices, you may choose to cut the cord
But first, ensure that your gateways, as well as, your VoIP Carrier’s network support T.38 faxes and a compatible modem passthrough functionality
VoIP Carrier’sSoftswitch / Feature Server
Ethernet
Network SideDigitalTrunks
Vega 400Trunking VoIP Gateway
Vega 50Analog VoIP Gateway
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Key Points to Remember Don’t underestimate the complexity of the PSTN and IP network Choose the right VoIP Endpoint for your application
Follow the industry – Use SIP for new installations Analog FXS or FXO Gateways for lines and key systems Digital Trunking Gateways for PBXs IP phones for new user installations Be sure you can support T.38 for faxes and bypass for modems Be sure you have a big enough IP pipe to add voice
SIP and H.323 VoIP Gateways can provide stand-alone routing and feature functionality
Use a Softswitch to manage numerous gateways and advanced features
VoIP carriers can provide connectivity beyond your private network Yes, you can cut the cord to the PSTN!