A hierarchical DHT overlay architecture based on P2PSIP is proposed to support a skype-like service. The IETF P2PSIP working group is standardizing a protocol to support any DHT in order to deploy services inside a domain. We extend its functionality to allow the interaction between peers of different domains. Furthermore, we perform an analysis of the routing performance and resource consumption under a skype-like scenario where VoIP calls are more likely to happen among users of the same domain.