Most questions would be based on your resume. They will concetrate what you did and not what they did :). So, please know in & out about your resume. Also, Please do not stuff your resume just for the sake of getting an interview call. Even if it did, it may be an issue if you did not answer their question on that topic. It is better to put stuff on which you are confident. For me, most of my telephonic interview had questions from Wireless Communications, Digital Communications, Random Signal Theory(Not in depth, for ex: How is a wireless channel distributed? why is it distributed like that? How does it's auto-correlation looks like? what are the other models available? Suggestions: Be good in Wireless Communications: Multipath, Coherence time, coherence bandwidth, time diversity, receiver diversity, doppler spread, WSS-US model, Rayleigh Fading, Rician Fading, Diversity schemes, Equalizers, OFDM, and the projects related to it. Digital Communication: Modulation schemes, BER, Basic Communication block diagram, etc. Last, but not least, in all these interviews there is no one-on-one answer. So, knowing the definitions related to this topics will not help. Try to related and study. A simple question, I would like to quote here, to say, how will their expectation be like. For Ex: Compare OFDM and CDMA. Hint you have is: With Shannon's channel thm, try to explain this. So, the interviewer is expecting you to apply a concept to two different technologies. Ex: Next question: How OFDM mitigates ISI? How CDMA mititgates ISI. (You must give an in-depth idea) Ex: Match Filters. How CDMA uses it. (Please go through match filter in-depth. This idea is used in CDMA Rake Reception. Please know, how it is getting used there. Also, Match filtering, is a kind of process that you can use for Channel estimation. Knowing the call processing procedure for any technology will also help. Please ,be sure with atleast one technology in depth. Last Suggestion: When the interviewer asks a question on a topic that you know well, start answering him that question with depth, so that your further questions will be based on it. So, this is like driving interviewer to an area that you are familiar. Else, it will be like he is trying to ask you different questions to know what you know. Best!