What size ONT for TalkTalk Business?

Looks like I'm finally getting somewhere with TT, but in discussions was told to think about placement on ONT which is "about A4 size"!
I'm guessing this is out of date info and refers to the older versions with BBU?

Yep.

It’s about three inches square now.

In reply to a post by burble:

Looks like I'm finally getting somewhere with TT, but in discussions was told to think about placement on ONT which is "about A4 size"!
I'm guessing this is out of date info and refers to the older versions with BBU?

Definitely out of date info.

The new ONT's (both Nokia and Huawei) are about the size of your current master socket, just a little thicker.

You would be provided the same ONT regardless of the OpenReach based provider you choose.

That's what I thought, although my present 5C mk4 is surface mount, so 2 1/2" deep.