How to setup a DID as dedicated fax?

I want to setup an incoming DID as a 100% dedicated fax - that always gives a fax tone to the caller.

I have read the previous Fax message thread on the board. Perhaps, I did not quite get the caveats and have not been able to get it to work. I am new to Asterisk - so maybe my understanding is flawed.

Here is what I tried:
Step 1) Add new SIP Extension 91
- all values default values

Step 2) Add new Incoming routing
trunk : <mylogin>-91
fax extn: system
fax email: myemail
fax switch: yes
set destination : extn 91
all other values are default values

Step 3) Point my DID ring-to-destination to <mylogin>-91@pbxes.com

Step 4) Call my DID and expect fax tone.

But it does not work.

PBXes Call monitor shows that PBXes gets the call, and considers 91 as ext-local and drops the call.

What is wrong?

I have re-read the thread
http://www1.pbxes.com/forum/thread.php?threadid=156&sid=

It is too vague, cryptic and open ended. I wish there is better alternative to this trial-and-error-hopefully-works approach. Are there any step-by-step instructions for normal configuration usage of Pbxes?

RE: How to setup a DID as dedicated fax?

Maybe the help text for option "Fax Switch" was a bit misleading. You need to turn the fax switch off to create a dedicated fax.

And it works ! direct ! with a number I have from Netappel.