This paper is concerned with building wide area computer networks. The environments concerned in this paper are: (1) Heterogeneous computer facilities. (2) Common resources for communications based in both packet switched and circuit switched networks. (3) Different implemented Arabic codes. The main objective of this paper is to define recommendations concerned with building a wide area computer network in the above mentioned environments. This paper could be considered as a useful guide to engineerS and researchers in the field of wide area computer networks in a typical heterogeneous environment.