First round was a screening round, they took interview for 30 mins and asked questions from IMS, SIP, C++ and aspirations.
2nd round was planned for half day with 2-3 rounds, 1st session took by 2 persons, asked questions on IMS entities(HSS, CSCF,AS) and SIP Registrations(3rd party registration), IMPU/IMPI, B2BUA from IMS. From C++, they asked about Virtual functions, Overriding, overloading etc... The questions were simple.
2nd Session took by Architect, asked about detailed flow for Media announcement in SIP/Megaco network...