AT&T Inc. (NYSE: T) is still searching for the real killer of its Houston DSLAM cabinet, which exploded back in late October, flattening an old man's fence and sending shrapnel hurtling as far away as 50 feet down the street. (See AT&T Investigates DSLAM Explosion.)

"We continue to thoroughly investigate the possible causes of the incident, but it's still too early to speculate on the outcome of our testing," writes an AT&T spokesman, in a reply to Light Reading's inquiries.

The spokesman says AT&T has assembled a strong forensic team and is working with "one of the world's top independent technical analysis firms" to gather evidence and probe the mysterious circumstances surrounding its broadband flambé. He adds that tests are time consuming and the company can't talk about the details of the investigation while it's ongoing.

In the early going, AT&T said it would check on all the things that might have caused the explosion. AT&T in November said gas leaks, electrical issues, and vandalism were possible causes.

A non-AT&T source close to the investigation says two causes are being vetted carefully these days. The first is a high-resistance short across the battery terminals inside the base of the cabinet. The second is a possible power supply problem with the Alcatel-Lucent (NYSE: ALU) DSLAM housed in the cabinet.

AT&T apparently does know enough about the explosion's cause to say that the DSLAM cabinet caper is not a network-wide concern.

"It's also important to reiterate that this was an isolated incident involving one box out of hundreds currently used in our network," AT&T spokesman Wes Warnock writes. "We remain confident in our plans to pass approximately 19 million living units by the end of 2008 as part of our initial deployment."

What's your take on the Amazing Exploding DSLAM? Let us know, in our brand-new poll: DSLAMBANG.

— Phil Harvey, News Editor, Light Reading