IT's how they base their pricing. Let me explain it.
There are two pricing models in the residential proxies space:
- Usage-based – you pay for the data used. The more requests you send and the more data used, the more you have to pay.
- PORT-based – you have unlimited bandwidth, but a limited number of requests you can send at any given time.
Basically, a PORT gives you another exit IP and increases the number of threads (connections) you can use.
And as in the case of bandwidth-based pricing, the more concurrent connections you send through the proxy network, the more PORTs you will need to avoid a bottle-neck effect.