Analog Troubleshooting

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We have found that often when installing Analog phone service via a Gateway or an Analog card installed in the PBX, it is often necessary to troubleshoot those lines for issues arising from faults in service on the lines. The following will provide some basic steps in order to verify service.

Step 1) If you are installing an Analog gateway or an Analog card this step is the most basic and the most important. Connect each line to the Gateway/Card one at a time and then call them individually. Make sure you have two way talk path, and in the case of the Gateway verify that the port light comes on and from within the Gateway you can view the status of the call on the Status page.

Step 2) Test Electrical properties of the line. The electrical properties are important in assuring service is at a level where users will not complain about voice quality. In the old circuit switch world, the equipment was switched and therefore all that was necessary was adequate voltage to open the circuit. SIP telephony equipment is software based and as such is more concerned with the actual specification. Make sure that your lines at lease meet the following minimums.

+/- 48 Volts idle rising to 90 Volts on a ring cycle Zero volts on a connected call

+15-35 mA of current on a connected call. This value is the most important.

To test these values you should have a multimeter or a ZIAD. Voltage can be tested by clipping on, however the amperage on a connected call must be tested inline with the circuit. This can be done by wiring your multimeter in line, or on a ZIAD can be done without any special modification.

The above values are guidelines and there is some play within the numbers. However if you are well outside these specifications then this will be a source of problem.

There is a link at the bottom of this page to the Sandman Web Page. On this page you will find a wealth of information on troubleshooting. Additionally Sandman sells a variety of devices to buffer and correct lines which are difficult. It is highly recommended that you make use of this fine resource.

Another item which must be borne in mind when troubleshooting analog service and that is that there is really nothing sold today in the continental US, which is a standard POTS line. Virtually all lines sold and provisioned are emulations of Analog service. It is this emulation which makes this troubleshooting difficult.

Also included on this page is a link to troubleshooting Grandstream Analog Gateways which goes into specific detail on Grandtream integration.

Analog Gateways

Grandstream FXO FAQ

Analog Line FAQ

  • We have found that Sandman is an excellent source for thorough analog troubleshooting information
  • insert basic analog troubleshooting

Testing International Calls

The following number calls to the automated date/time service in Australia so you can test international calls without bothering anyone:


NOTE: Your rate carrier needs to allow you to call Australia for this test to work.

Another test number to a hotel in Mexico: 011 52 664 633 3900

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