How can a broker be a market maker and non dealing desk at the same time?

For example, on Oanda’s site I see they are a market maker but they also state:

[I]3. Our trade execution is seamless. All transactions are 100% automated without any “dealing desk” intervention. Trades are executed instantly and settled immediately—no delays, no rejections, no requotes.
[/I]

How is that possible? Aren’t the two mutually exclusive?

Dealing desk means orders going through some kind of potential human intervention process. OANDA’s market-making is fully automated, thus not a dealing desk.

Just because broker posts something on their website, doesn’t mean its a fact. None of them will tell you the truth, but Oanda has some crazy non-existant spikes, so they are definitely not a real market broker, they are on the other side of the trade, not anyone else.