Transcript Understanding Quality of Experience Diagnostic Tools – Line Test and
Understanding Quality of Experience
Diagnostic Tools – Line Test (or how to save money and increase customer satisfaction)
Agenda
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
• • • • • • •
Who is Legerity?
Quality of Experience improvement tools
– –
Automated Call Quality Monitoring In-Premise Loop Diagnostics Loop/line test background Key line test specifications Descriptions of CPE line tests CPE line test software suite example Summary
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Who is Legerity
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
• Legerity, now part of Zarlink Semiconductor, is the leading supplier of voice interface integrated circuits – FXS (POTS interface) solutions for all points in the network from the central office to residential gateways, and everywhere in between • MSAN, DLC, etc. and Enterprise gateways (PBX, etc.)
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QoE Improvement Tools - Overview
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
• Automated Call Quality Monitoring – Many VoIP CPE devices (e.g. Cable EMTA’s) now automatically monitor calls and log and store metrics • • • • • Listening quality and conversational quality (MOS) scores Residual echo return loss scores Packet loss analysis Broadband signal quality IP and call processing message logs • In-Premise Loop Diagnostics – Many VoIP CPE devices now have the capability to performing remote tests on the in-home wiring and provide troubleshooting data – The system operator can remotely perform these tests returning either simple pass/fail results or more extensive test reports
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In-Home Wiring Creates Challenges …..
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
INSIDE HOUSE WIRING is one of the top causes for Trouble Reports.
Due to the high rate of trouble tickets related to inside wiring, VoIP service providers recognize the need for CPE line testing
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Loop Diagnostics Background
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
• • • ‘Metallic Loop Testing’ or ‘Line Testing’ involves testing for faults in the ‘copper plant’ (telephone wires) Line testing was originally deployed in central offices using large expensive test heads that tested each wire pair one at a time – The test head is connected to each telephone line via a switch or relay Today, line testing also needs to be deployed in remote equipment, DLCs, MSANs, PBXs and even residential gateways (CPE), etc.
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VoIP CPE Line Testing
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
• Service providers recognize the need for VoIP line testing – – – – US Cable MSOs (e.g Comcast, Cox) require GR-909 line testing in EMTAs US ILECs (e.g. Verizon) require GR-909 line testing in FTTH gateways Vonage deploys GR 909 line testing in residential gateways (ATA’s) DSL Forum TR-122 requires TIA-1063 line testing (p. 28) • Benefits of deploying remote line testing capability in VoIP CPE – – – – – Automated, remote testing capability eliminates costly truck rolls Enhances call center support capabilities to identify simple faults Reduces maintenance costs Decreases mean time to repairs Increases customer satisfaction through quick problem resolution and therefore reduces customer churn
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GR-909 Excerpt (Section 12.4 – Testing)
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California 8 www.ITEXPO.com
TIA-1063 Line Testing Excerpt
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California 9 www.ITEXPO.com
Test Descriptions
Hazardous Voltage Test
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
• • • Tests for the presence of hazardous AC or DC voltage on the line – – AC >50V or DC >135V Force Zero Voltage (to discharge the line) and measure AC and DC Voltages • Tip to Gnd, Ring to Gnd, Tip to Ring – Indicates that a hazardous is present on the drop Possible Cause – – Tip or Ring shorted to home AC power line (110V-240V) Tip or Ring shorted to other equipment DC power supply Possible Symptoms – – – – – – No Dial Tone Can not dial out No phones ring Phone interface in Protection State 60Hz/50Hz buzz on line Phone may ring at 60Hz/50Hz
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Foreign Voltage Test
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
• • • Tests for the presence of foreign AC or DC voltage on the line – – AC >10V or DC >6V Force Zero Voltage (to discharge the line) and measure AC and DC Voltages • Tip to Gnd, Ring to Gnd, Tip to Ring – Indicates that a hazardous or foreign voltage is present on the drop Possible Cause – – Connected to PSTN Tip or Ring shorted to other equipment DC power supply Possible Symptoms – – – – No Dial Tone Can not dial out No phones ring LC in Protection State
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Resistive Faults Test
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
• • • Tests DC resistance – Force DC current, measure voltage, compute the Resistance (Ohms law) • Tip to Gnd, Ring to Gnd, Tip to Ring – Resistance below threshold indicates a fault Possible Cause – – – – Tip or Ring shorted to cable shield Moisture in cable Protection device shorted Staple or nail shorting Tip and Ring Possible Symptoms – No Dial Tone – – No incoming calls 50Hz/60Hz buzz on line due to longitudinal imbalance
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Receiver Off Hook Test
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
• • • The test discriminates between a resistive fault in the loop and a receiver-off hook condition from properly working terminal equipment – Indicates that a telephone receiver (or other CPE) is off-hook as opposed to a resistive fault – phone has non-linear signature, different than a resistor Possible Cause – One of multiple phones left off hook Possible Symptoms – – No Dial Tone Can not receive calls
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Ringer Equivalence Test
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
• • • This test measures the CPE equipment’s AC ringer impedance – 20Hz AC Test – tests to see if the FCC part 68 REN load is within range • • REN too high – excessive load, could cause pre-trip faults REN too low – phone is probably not plugged in Possible Cause – Too many phones connected • Exceeds 5 REN – No phone connected • Or less than 0.175 REN – – – Open in loop Ringer is open Faulty phone • Ringer capacitor shorted Possible Symptoms – Phone does not ring – – – Line ring trips after a short burst of ring (pre-trip) Not all phones ring Low ring loudness
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GR-909 Pass/Fail Criteria
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California 16 www.ITEXPO.com
Line Testing Software
Example
Legerity’s VeriVoice™ Test Suite Software
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
• • VeriVoice ™ Test Suite is a subscriber line test software package for VoIP equipment – Provides outward, GR-909, tests and/or inward self-tests – GR-909 Tests include: • Line Voltage Test – Hazardous and foreign voltages • • Receiver Off Hook Test Ringer Equivalence Test – No phone or too many phones • Resistive Faults Test – Wiring shorts VeriVoice can be remotely run, providing pass/fail or measured results to the system operator
VeriVoice™ Test Suite Demo 18 www.ITEXPO.com
VeriVoice™ Test Suite Packages
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
• Two distinct test packages corresponding to two different levels of coverage – – VeriVoice™ Auditor • Outward looking
pass/fail
line tests VeriVoice™ Professional • Outward looking line tests
returning measured results
and inward self tests – – The outward looking tests check customer equipment & copper pair leading to it The inward looking self tests check the VoIP equipment itself.
VeriVoice Auditor VeriVoice Professional Description Tests
Outward Tests Line Voltage Receiver Off Hook Ringer Equivalence Resistive Faults All Outward Tests Inward Tests Loopback DC Voltage DC Feed Ring On/Off Hook Read Battery Conditions 3 3 3 3 ● 1 ● 1 ● 1 ● 1 ● 1 3 3 ● 1 ● 1 ● 1 ● 1 ● 1 ● 1 ● 1 ● 1 ● 1 ● 1 ● 1 Checks for hazardous and foreign AC and DC voltages on the drop Tests for longitudinal fault, off hook restive fault, and receiver off hook Tests the impedance of the line and returns a fail if the REN is too low or too high Measures three element resistance Performs all outward tests in correct sequence Enables receive-to-transmit signal loopback by two different methods Verifies that the line circuit has the ability to drive the voltage rangers required for the normal operation of the line circuit Measures the voltage and current across a known test load resistor using the DC feed profile that has been programmed Verifies ring signal generation, drive capability and ring tip Calculates on-hook and off-hook conditions on the line using the test-load resistor Reads the battery voltages connected to the line circuit
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Things to look for in line test software
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
• Is it easy to integrate with the other software that is running on the device?
• Is it fully tested, characterized and validated against FXS actual silicon?
– Or is it merely sample code?
• Has the software been optimized for the particular FXS silicon in your product?
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Summary
September 10-12, 2007 • Los Angeles Convention Center • Los Angeles, California
• • • Metallic Loop Testing Systems (MLTS) or Line Testing has been used for many years in central offices, using big, expensive test heads As central office line cards move closer to the home with neighborhood DLCs and MSANs, etc., and residential gateways in the homes, the use of these test heads is no longer practical In the NGN VoIP networks the most effective way to implement line testing is through the deployment of software running on processors in residential gateways and other remote line card equipment • Many VoIP operators are deploying remote line testing capability in their residential gateways resulting in reduced customer support costs and increased customer satisfaction – More profit and less customer churn!
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