I found some information about this number:
Tax Defense Netowork
13901 Sutton Park Drive S. Suite 100
Jacksonville, FL 32224
904-421-4410

I represent Tax Defense Network and I'd like to provide some information for your users. We only call people who have filled out a form asking for a call regarding their tax debt. We are a professional tax firm and do not do telemarketing. If you submit your phone number we feel obligated to call you until we speak to you. If you do not want to be called just answer the phone and tell us not to call and we'll take your phone number out of our system. Anyone that states that they don't know how we got their number should think about that. Especially since we only call those people who have asked for a call.

Dear Tax Defense Network worker ...

Please search 888-829-6911 and 303-900-1340 regarding unsolicited recorded messages to cell phones from Tax Defense Network.

If this is you folks, then I guess that your statement is, well, a lie.
If not, then there is an entity that is putting your company in an uncomfortable position.

My cell phone has been called in excess of 20 times. My cell phone is unlisted.  I have not submitted any info to TDN regarding my taxes.

In all fairness ...

This reply is in reference to the comment I made above.
If you are getting calls from these folks, the calls are indeed legit and not telemarketing.

I called 888-829-6911 tax defense network, to demand that the calls stop or to provide some kind of proof of "my inquiry".  As it has turned out, some mental giant, who apparently does not know his own phone number had made the request.  The rep. from TDN was polite, identified the person that made the inquiry (if it had been someone I know, I then could take action for misrepresenting my phone number).  The rep. from TDN removed my number from there system.

In short, give them a call to remove your number and identify the goofball that used your number, either by mistake or by belligerence.

Thanks.

Tax Defense Network only calls people that have completed an online form asking for help. If you did not complete an online form maybe your spouse or someone else you know did. If you do not owe a tax debt and are not in need of our tax attorneys to help you then please just tell us you'd like to "opt-out" and we will stop calling you immediately. Believe me we do not want to waste time calling anyone that doesn't need our services when so many out there do owe the IRS and we can provide them with what they are seeking- relief from IRS collection action.