These are the proceedings of IPTComm 2008 - the Second Conference on Pr- ciples, Systems andApplications ofIP Telecommunications-heldinHeidelberg, Germany, July 1-2, 2008. The scope of the conference included recent advances in the domains of convergent networks, VoIP security and multimedia service environments for next generation networks. The conference attracted 56 s- missions, of which the Program Committee selected 16 papers for publication. The review process followed strict standards: each paper received at least three reviews. We would like to thank all Program Committee members and external reviewers for their contribution to the review process. The conference attracted attendees from academia and industry. Its excellence is re?ected in the quality of the contributed papers and invited talks. Additional industry talks and - plied demonstrations assured a synergy between academic and applied research. We would also like to acknowledge and thank our sponsors, many of whom s- portedtheconferencegenerously: NEC, AT&T, Codenomicon, IPTEGO, EADS, Cellcrypt, MuDynamics, SIP Forum and EURESCOM, Finally, we would like to thank all the researchers and authors from all over the world who submitted their work to the IPTComm 2008 conferenc