The telecommunication industry has been successful in turning the Internet into a mobile service and stimulating the creation of a new set of networked, remote services. Most of these services now run or are supported by cloud computing platforms. Embracing cloud computing solutions is fundamental for the telecommunication industry to remain competitive. However, there are many legal, regulatory, business, market-related and technical challenges that must be considered first. In this paper, the authors list such challenges and define a set of privacy, security and trust requirements that must be taken into account before cloud computing solutions can be fully integrated and deployed by telecommunication providers.