'extensive contacts' is correct and usable in written English.
Example sentence: She developed extensive contacts in the film industry during her time in Los Angeles.
The two men have extensive contacts in the business community.
It has extensive contacts in Mr. Putin's administration.
He has extensive contacts along the pirate-infested Somali coast.
The mafia had extensive contacts with senior Russian politicians.
"He has a lot of money and extensive contacts around the world.
The upshot was extensive contacts with eastern European soloists, conductors and orchestras.
It originally said MI5 had extensive contacts with Begg before and after his trips to Syria.
Thiam has been courted by politicians and has extensive contacts outside business.
Black Cube's employees have extensive contacts within the Israeli government and intelligence world.
Those who know Ornstein call him a risk-taker whose extensive contacts facilitate deals.
Rio Tinto viewed Steinmetz, who was rumored to have extensive contacts in Israeli intelligence, as a suspicious interloper.
