Most companies operating a call centre will use call monitoring software. The software normally logs the number of phone from where the call came. It will not matter if you call them using a NGN or from a normal number. If you block your number when you dial, then they will not have your number. If you use a third party service, such as a calling card, it might possibly be different.
A little tip for when you complain. As the call software records your number, you can always point this out to the company when they try to bluff you and claim that they have no record of your call. Just tell them to run a search based on the number you have been calling from. They will then be able to retrieve the call from their call system. If this is as clear as mud, contact me and I will try to explain more clearly.
Regards
Copperbean