Understanding Over-The-Counter Networks

Beginner Questions
1

I’m reading about Over-The Counter Networks and I understand its basically via commercial or investment banks rather than an exchange. So this mean prices are not always transparent

What i’m trying to understand is - does this mean if the broker is using an OTC it cannot be using ECN or DMA?

It has to be a Market Maker or possibly STP?

I ask because i’m trying to understand what IG is. I know they have DIrect Forex for DMA but it simply refer to the other trade methods as OTC. I have no idea if that means its a Market Maker or something else

2

As usual, there is no central marketplace for OTC trading in the understanding of exchange.
Another important point is that lisitng rules and requirements for OTC are often lower than for the regulated markets (for example, OTC Pink Sheet lisiting in US).
In the meaning of Forex, OTC used to name the execution type when the broker does not provide you with access to the regulated market but execute your orders using own resources.