SIP demystified / Gonzalo Camarillo
Wireless internet access over GSM and UMTS / Manfred Taferner, Ernst Bonek
Annual review of communications / IEC - International Engineering Consortium
Ovum forecasts : global IP and broadband markets / Richard Kee ... [et. al.]
IP Interconnect : commercial, technical and regulatory dynamics / David Rogerson...[et. al.]
IP voice services : European corporate market forecasts, 2002-2007 / Margaret Hopkins