Q.	Why should Service Providers and Network Management/Maintenance Groups use NETLINK 423/424?
A.	In today's ISO 9000 environment, Service Providers are required to guarantee high quality and availability of the telephone services they deliver to their customers, often in the form of regulated Service Level Agreements or Guarantees. In addition, the hidden costs of NOT having a test system such as NETLINK 423/424 which actually measures (quantitatively) the Quality of Service of end-to-end service actually delivered to the customer premises include: Customer dissatisfaction Customer turn-over (churning) Repeat service calls Unnecessary and ineffective telephone replacements (e.g est. $25m per annum in Australia) Inefficient and subjective fault reporting and fault identification methods Inability to detect emerging systemic problems before they become endemic Speed restrictions, intermittent problems and disconnections for Internet modems.
Q.	Why can't we use the loop monitoring functions and test heads already built in to our Local Exchanges?
A.	Because at best, these perform "superficial" tests (e.g. dc volts, insulation resistance, noise) on copper loops attached to the exchange. They do not test the overall (end-to-end) Quality of Service (QoS) delivery. They cannot identify problems with electronic access networks (pair gain systems, voice frequency amplifiers, line multiplexers etc). They cannot identify exchange and inter-exchange problems. They cannot identify frequency response problems and impedance matching problems (which cause excessive sidetone and echo).
Q.	Our network is largely, and increasingly, "digital" and therefore problem free. Why should we use NETLINK 423/424?
A.	The network is becoming much more complex and unfortunately, despite optimistic claims, "digital" is far from problem free. In fact, problems due to digital "noise", synchronisation problems, packet losses, wrong software gain settings, impedance mismatch problems, unstable signal processing systems etc are rapidly increasing not decreasing.
Q.	Why were the NETLINK 423 and 424 Network Quality Testers developed?
A.	NETLINK 423 and 424 were developed as Telco's became more aware of their responsibilities as Service Providers, and as Telco's (and other organisations) around the world recognised the benefits of Quality Assurance (e.g. ISO 9000). As part of their customer service guarantee obligations in a Quality of Service (QoS) environment, Telco's increasingly need to ensure the quality of the end to end telephone services which they provide to their customers, at the time and at the point of service delivery. The installation technician making a phone call to another technician and checking that the call "got through" is no longer "good enough". NETLINK 423 and 424 were developed to provide Service Providers with simple-to-use tools, specifically to ensure that the services, which they actually deliver to their customers, meet the Telco's obligations and their customers' expectations . This is becoming even more important with increasing competition from competitive carriers, from mobile and wireless services, and from potentially lower cost VoIP (Voice over Internet Protocol) products.
Q.	How does the COMLINK Software fit in with NETLINK 423 and 424?
A.	COMLINK Access is a single user Windows application for field staff to initiate network tests via their computers, and to display the results in a graphical format which is easy to understand . COMLINK Access is designed to enable all NETLINK users who have access to a computer, to perform network tests, to build up a database of their test results to visualise what is happening in the network and to develop a knowledge base to help them to identify faults . COMLINK Executive (Administrator plus "Robot") and COMLINK Manager are for Service Providers with an internal data network (intranet) to deploy Network QoS Management throughout their organisations. COMLINK Executive allows the system administrator to manage a network of NETLINK 424 Test Responders (or several groups of 'regional' Responders) e.g. as a 'Test Call System'. It also automatically gathers the results of all NETLINK tests throughout the network, and stores them in a network database, to be accessed by technical support and specialist staff via their Intranet. COMLINK Manager is a network user Windows application for technical support and specialist (e.g. office based) staff to view and analyse the results of field tests in real time e.g. to provide feedback and assistance to field staff or to analyse network design problems. COMLINK Manager also enables support staff to print NETLINK test reports and to perform statistical analysis on NETLINK test results stored in the Service Provider's database.
Q.	Why should I (an end user/field operative) use NETLINK 423? What's in it for me?
A.	Its use will make you much more productive. You will single handed be able to identify faults and problems in a fraction of the time which two engineers would take using conventional test equipment, and would often miss. You will present a much more "QoS" image to your customers on behalf of your employer, by testing thoroughly and professionally. Especially if you are also using the associated COMLINK Access Software, you will easily learn to visualise the whole performance of the network, and quickly become a better "network detective". NETLINK will enable you to identify problems on the spot, and therefore minimise customer dissatisfaction, and unnecessary repeat service calls by yourself and/or your colleagues.
Q.	How do I use NETLINK 423 Testers and NETLINK 424 Responders?
A.	Very simply! Answering for the NETLINK 424 Responder first: Typically each NETLINK 424 will act as a test destination for up to 40-50 NETLINK 423 users (depending on test traffic). All you have to do is to install the Responder(s) at one convenient location (or a number of regional locations) preferably close to an exchange MDF. Then you connect up their Mains Adaptors and turn the units on. Now just: Check that they have the correct time and date Check that their test impedances are set to match their exchange Connect them to line (2-wire POTS) (Check the User Guide for details). Now to using NETLINK 423 Testers: You can use a NETLINK 423 to test the network switching and transmission performance at any 2-wire POTS connection, anywhere in the network, or behind a PABX connected to the network. This is basically as simple as A,B,C, (D). Press [B] to set the impedance (if required) Press [C] to check the clock (if required) Press [A] to perform the test Press [D] and [C] to display the test results. (Check the User Guide for details).
Q.	What are the most commonly occurring network problems?
A.	Apart from billing disputes, and occasional damage to cables due to excavation etc, the most common problems are Transmission Problems. These include: Wrong loss settings: · Especially if the losses are asymmetric, these cause serious speech intelligibility problems (one end speaks too loud, the other end too soft) and modem problems (modem "training " sequences assume the circuit is the same both ways). Impedance mismatch problems: These cause speech unintelligibility due to sidetone, echo, frequency response and asymmetry, and also lead to modem problems. Low signal to noise ratios: Caused by excessive quantisation (and signal compression), poor SNR can severely degrade modem performance. Noise: Noise is a common cause of POTS, modem and fax problems. NETLINK measures average noise, peak noise, impulse noise (and signal to noise ratio). Data Packet Delays and Losses: These problems are likely to increase rapidly with VoIP and VoATM etc.
Q.	What do I do if nothing happens when I switch my unit on?
A.	This usually means that its battery needs charging. (Refer to the Troubleshooting Section in your User Guide).
Q.	What do I do if I get an Error message on the display during a test?
A.	Refer to the Test Error Messages Explanation Section in your User Guide.
Q.	What do I do if I still get a Calibration Error message, even after I have Autocalibrated my unit?
A.	Check that you do NOT have the Line Test lead plugged into the Phone Connector.
Q.	What do I do if I get a Limit Message at the end of a test?
A.	If it is SLOPE Asymmetry, then change your test impedance and repeat the test. Refer to Asymmetry in the Interpretation of Test Results Section of your User Guide. Otherwise, refer to the Limit Messages Explanation Section in your User Guide.
Q.	What is the cause of severe "ripple" in the frequency response?
A.	This is almost certainly due to a faulty loaded cable e.g loading coils which have been damaged or incorrectly fitted or removed.
Q.	How do I determine if a fault is in the Access Network or the Exchange Network?
A.	Repeat the test from the exchange MDF. The "contribution" of the Access Network is the difference between the test results from the Service Delivery Point and the results from the MDF.
Q.	What do I do if I get "funny" (anomalous) results?
A.	The most common cause is Call Waiting Tones interfering with the test. You should have heard them in the Monitor Speaker (eg.typically beep beep every five seconds). Turn off Call Waiting and repeat the test. Don't forget to turn Call Waiting back on again after you have finished your tests, if that is the customer's preference. Another potential cause is a parallel connection of modem or facsimile machine tones. These are normally very audible if you listen to the Monitor Speaker during the test call.
Q.	What is the cause of the Destination (eg. a NETLINK 424) not answering the test call?
A.	The Responder may be busy on another test call. OR You have inadvertently entered an incorrect destination telephone number. Check that the number is correct, including area code. Tip: Enter your most commonly used destination number in your NETLINK 's Phone Book Memory location 0. Your NETLINK will automatically recall this number for you whenever you switch it on. OR You have changed between a PABX extension and a direct PSTN line without adding or deleting the PABX access digits (prefix).
Q.	What do I do if the Destination answers and sends answer tone, but my NETLINK displays No Response and does not proceed with the test?
A.	It is most likely that there is too much loss (and/or noise) between your unit and the Destination, for your unit to recognise the Responder answer tone. You can use Tone Monitor Test to check this. In Tone Monitor Test, your NETLINK should display a frequency of approximately 2100Hz and a level of at least -35dBu for a few seconds while the Responder sends answer tone. The excessive loss can be caused by a faulty loaded cable. This can put big "holes" in the frequency response (e.g at 2100Hz). You can perform a Traffic Route Test which tests call progress and call switching, and measures Noise and Return Loss. A faulty loaded cable will typically give approximately 9dB Return Loss at all impedances ( TN6, TN12 and TN1). To confirm and identify the problem you can move closer to the telephone exchange and repeat the test. Performing tests on very long lines with the wrong test impedance, can degrade the signal to noise ratio to the extent that the NETLINK internal modems have difficulty in communicating. If the Traffic Route Test indicated that you have selected the wrong test impedance (i.e. the Return Loss at your test impedance is lower than the Return Loss at the other test impedance) then change your test impedance and repeat the test.
Q.	How do I interpret test results?
A.	Refer to the Section on Interpretation of Test Results in your User Guide. There is also a Training Course available which will help you with this. If you use the COMLINK Access Software with your NETLINK unit, you will see the test results in a simple to understand graphical format, which will help you to understand what is going on. If your Company is using COMLINK Manager (Results) Software, then your supervisor can access your test results in real time, and help you to interpret the results.
Q.	My results stored in my NETLINK have "disappeared". What has gone wrong?
A.	You have an origin/destination " viewing criteria" set, and you forgot to press the [C] key to display ALL the results, beginning with the latest. Refer to the Section on Viewing Results in your User Guide.
Q.	I am trying to access one of NETLINK's sub-menus, and I've ended up "somewhere else". How do I get out of it?
A.	Wherever you are, you can always press the [#] key ("Exit" or "Backspace") to get back to where you are meant to be, or back at the Main Menu. Don't worry, you will never lose information or get into trouble by pressing the [#] key, as many times as needed.
Q.	Is technical support available?
A.	Definitely. E-mail tech.support@edlaus.com, or fax +61 3 9762 3640 in the first instance, for immediate assistance or advice. Please feel free to use the same contact for any input, or for assistance with any other needs.