It could be that the bluetooth module was never activated at the dealer. See other suggestions in the following thread.

BMW Bluetooth Telematics Control Unit 2000 2006 E46 x5 x3 Z4 Used | eBay

Perhaps the bluetooth module was never activated?

Here are some other suggestions.
Bluetooth Phone Pairing -Step by Step HELP PLEASE!! Moto V551 - Bimmerfest - BMW Forums

I found a post in this forum that addresses the pairing issue. The pairing button is inside the console.
Xoutpost.com - powered by BMW X-sav Enthusiasts!

Perhaps. How would yo activate the module without going to the stealer? I read the article but did not mentioned how to activate the module.

The last link just bring me to the main page of xoutpost.com

The pairing button we are looking for should be inside the console. Did you check there?

search the E53 forum here for bluetooth pairing 2005 X5. Go to the third page and look for a thread that began 9/6/2005

Checked. Nothing inside the center console

If that is the case, have you tried the Xoutpost post I mentioned.

I also found this one.
orums.bimmerforums.com/forum/showthread.php?1760741-2005-X5-Pairing-April-05-build-date-R-T-button

Let's see if this works

bimmerforums.com/forum/showthread.php?1760741-2005-X5-Pairing-April-05-build-date-R-T-button