Home phone from Plusnet is actually BT?

[#1]

So my brand new phone service got activated today, great.
But when I dial 100 I get "Welcome to BT..." 
So... errr...  Why don't I hear "Welcome to Plusnet..." or some such?

[#2]

BT customer services is on 150  if you are a BT customer. If not, you get a message that "you cannot call this number from this line".
I assume 100 goes to BT because BT are providing operator services for Plusnet but not customer services.

[#3]

"You cannot call this number..." cool.  Thanks for pointing me in the right direction.

[#4]

We provide our service on BT Wholesale's network

[#5]

I was under the impression that PlusNet were owned by BT, bought in 2007ish?
🙂

[#6]

yep.