The advance in vehicular and wireless communications has contributed to the release of Vehicular Clouds which makes it possible to release various multimedia and storage services. However, providing a communication service which allows to cope with the high mobility of vehicles, and the limited availability of wireless resources, while guaranteeing a high quality of service (QoS), is a challenging issue. This paper proposes a cloud Communication-as-a-Service (CaaS) to: a) enable a continuous communication to vehicle located beyond the area uncovered by Roadside units; b) guarantee the Quality of Service QoS (QoS) in terms of delay, throughput and packet loss rate; and c) cope with resources limitation in vehicular networks. To implement these solutions, a Vehicular Cloud architecture (V-Cloud) which is composed by three layers, is proposed. The first layer, entitled Vehicular Cloudlet, consists of a set of vehicles connected to the network and organized into groups, creating a tree topology. The second layer, named Roadside Cloudlet, is a local cloud established among a set of neighboring RSUs. Finally, the third layer is the central cloud which is a cloud established among a group of servers in the Internet.