I am pretty sure I have pinpointed this audio problem to Cell phones...

Even though they are on mute/silent... I still get this interference when a cell phone is near and gets a phone call.

EXAMPLE: http://www.lifeinneworleans.com/sound-problem.wmv

Short video clip with audio interference.

Ok...So I know what the problem is...

NOW: WHAT CAN I DO TO LIMIT OR KILL THE PROBLEM COMPLETELY?

I try to tell everyone to TURN OFF their cell phones when doing a shoot... but most people do not truly understand that... They simple turn it on silent.
And the crapola happen again... causing us alot of wasted time.

Shooting with SONY VX2100 or SONY HDR-FX1... with Sennheiser MKE300 MIC... via mini-jack.

Thanks for any input...

Cell phones "call home" every few minutes when powered up to let the system know where to route calls even when they're not in active use. The only real solution is a complete power-off for all phones within the vicinity of the set.

You might be able to reduce the problem by changing the mic from the unbalanced Sennheiser to a balanced mic and XLR adapter such as a Beachtek. Balanced mic cables are less susceptible to outside interference. But the only real solution is to let the word get out that you're a tyrant who will smash every cell phone on sight <grin>.

it's not a real "Solution" to the problem, but a way to deal with it - have an intern/buddy/lackey hold all the phones just off set and be in charge of them - that way no one has to worry about missing a call, and the phones are at a safe distance from all of the gear. Just a thought.