Customer Premise Equipment
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COMT 220 1 Customer Premise Equipment COMT 220
description
Customer Premise Equipment. COMT 220. Definitions. CPE - Customer Premise Equipment Correctly defined as “anything the customer connects to the network” In practice we use CPE to mean “equipment other than simple terminals” (phones, PCs, etc.) - PowerPoint PPT Presentation
Transcript of Customer Premise Equipment
COMT 220
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Customer Premise Equipment
COMT 220
COMT 220
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Definitions
• CPE - Customer Premise Equipment– Correctly defined as “anything the
customer connects to the network”– In practice we use CPE to mean
“equipment other than simple terminals” (phones, PCs, etc.)
• We will discuss mainly voice, but the arguments apply to video and data also
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Rationale
• Placed between End-Users and CO connections
• Provide on-premise functions• Make cost-efficient use of CO connections
User
User
User
COCPE
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Different Types…
• PBX - Private Branch Exchange– Full Premise Based Switching
• Key System– Smaller System, usually non-switching– Difference to PBX often unclear
• CENTREX– PBX functionality, but implemented in
the Central Office Switch
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Switching Principles and Methods
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Cross-Point Switching“Space Division Switching
”1
1
4
4
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Three-Stage Switch
From Stallings, Voice and Data Communications.
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Time Division Switching
• Each Line Card “Samples” the inbound signal (8000 times per second, each sample is taken over 0.125 msec)
• While the cards collect the next sample (during the next 0.125 msec), the Time Slot Interchanger collects all samples and delivers them to the correct line card outputs
• The TSI must process 8000*2*(number of conversation) samples
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Time Division Switching
TSI
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PBX “Block Diagram”
PBXSwitching
System
Administration
LINES
TRUNKS
AnalogPhones
DigitalPhones
SpecialWorkstations
LocalSwitched Access
IXCSpecial Access
Private Lines
CTIMaintenance SMDR
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Packet Switching?
PBXSwitching
System
LINES
TRUNKS
AnalogPhones
DigitalPhone
DigitalPhone
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Categories of Features
• Features for the System User (Internal Customer)
• Features for the System Administrator
• Features for the Caller (External Customer)
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Handling Outbound Calls
• Call destination restrictions• Least cost route selection• Automatic redial
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Handling Inbound Calls
• Routing Calls– Attendant– Direct Inward Dialing
• Handling Unanswered Calls– Call Forwarding -- General– Call Forwarding -- Busy/No-Answer– Hunt Groups– Queuing and Message Services
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Handling Unanswered Calls
• Hunt Groups• Queuing• UCD
– Universal Call Distributor
• ACDs– Specialized PBX software for inbound
call handling
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PBX Capacity
• Traffic (usually measured in call minutes per hour)– How Many Simultaneous Calls
• Processor– Total Calling Volume– Busy Hour Call Attempts
• Physical Interfaces– Stations and Trunks
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“Programming a PBX”
• Moves, Adds, and Changes (MAC)– Establish New Service– Disconnect Service– Change Features On Existing Service
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Adding an Analog Station
• Physical Install• Assign Extension Number• Assign Class of Service and Other
Features– Often uses a template (or “Table”)
1234A
B
C
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Adding a Digital Phone
• Physical Installation• Define Feature Buttons on the
Digital Phone• Define Line Appearance Buttons• Assign Extension(s) to Line
Appearances• Assign Class of Service
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Button Assignments
A
B
C1 2 3
4 5 6
7 8 9
* 0 #1
2
3
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Button Assignments
A
B
C1 2 3
4 5 6
7 8 9
* 0 #1
2
3
Line 2
Line 1
Hold Xfer
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Extension Assignments
A
B
C1 2 3
4 5 6
7 8 9
* 0 #1
2
3
1234
5678
Hold Xfer1234
5678
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Extra Slides
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Multi-Stage Crosspoint Switching - Concept
