The moment Gustav arrived, Roland immediately told Gustav and the others his plan.
Basically, Roland would call Razor's number from an unknown sim and track him from there.
With the tracking skill and knowledge, he just bought, Roland learned a lot of ways on tracking him through a phone call.
The others involved the use of supernatural powers that he did not know of, while the most basic tracking was to track him by accessing his current location through global position system or gps or by locating the cell tower that the call receiver was answering the phone from.
There, Roland could just micro locate him easily and even pinpoint his location almost immediately.
Normally, police need a warrant before they could perform such operations as it was kind of considered as a privacy breach, and hence illegal.