Hi our building was hit by lightning yesterday. Since then our 2800 series has intermittent ISDN issues - cracking - calls being cut off as soon as they are answered.. but then other calls are OK so I dont think my isdn ports are fried.
Here is an ISDN dq931 debug of a failed call - does it mean anything to anyone?
Re: 2800 series CCME - lightning strike ISDN issue
You can see the router sends 2 alerting messages and the attached ISDN network is not happy with this. Normally I would be thinking this is a software issue, but past experience with BRI cards and lightning strikes suggests that your card may have been fried :-(
You may even find that if you do a reload the card no longer shows up in the config at all.
As a FYI, the existing protection mechanisms on the ISDN line side of the VIC2-2BRI-NT/TE interface meet all recognised standards and have worked very well in locations all over the world.
We have, however, observed some cases where BRI cards have been damaged by line surges or external voltage transients.
The VIC2-2BRI-NT/TE card was designed and tested to meet standards for 'on premises' usage. This means that the external NT1 device is expected to provide an adequate level of isolation to prevent common mode voltage pass-through from the Service Provider network side U interface to the Customer Premises terminal side S/T interface.
In this situation, the best course of action would be for the customer to have the Service Provider incorporate a higher level of protection at the cabling entry point to limit external voltage surges from even reaching the NT1 device itself.
This is often referred to as 'direct strike protection' and a good example is detailed in the following Telstra Australia documentation -
A picture of the surge (lightning) suppressor can be found on page 59. More details on these surge suppressors are on pages 69 and 70.
As mentioned earlier, the VIC2-2BRI-NT/TE card meets all relevant standards and specifications for interconnecting to public networks. There is still a requirement of adequate external line protection at building point of entry, especially in locations that are susceptible to lightning or external transients.
You may want to consider requesting additional line protection on your ISDN services to prevent these kind of problems in the future.
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