Static burst during call - anyone heard anything like this?

Heard this static burst on a customer’s system yesterday, they’ve been having a number of these plus some garbled speech and dropped calls, we haven’t been able to find any errors in the Asterisk logs/console related to this and we’re running tcpdumps hoping to capture one and get a closer look. Anyone have any idea what this might be?

http://s000.tinyupload.com/index.php?file_id=00871346650226676798

LIghtning strikes near your DAHDI analogue wires? You haven’t told us anything about your configuration.

do you use a headset ?

It’s a group of SIP hardphones (with computers piggybacking on the phones) connected to the Asterisk server on a gigabit LAN with a gigabit connection to the outside, calls to the outside running through a SIP trunk. These static bursts have happened on calls with no headsets involved.