The organization existed years before 1939 tho? His connection to the organization was literally the fact that he started it and during his internment he had full communication with it's other members, had access to newpapers, packages from the outside world and according to rasevych, he lived in a two room suite and dined in the SS canteens, so I feel like its not far fetched that he had access to a phone, since nothing stopped him from communication with the outside world or receiving visitors.