After applying on their career web page, I was contacted via email in just a few days. I set a date for the first interview with the recruiter. She was very nice and explained to me what the job entailed. This first part wasn't exactly an interview, as I had expected, just a call to schedule the first technical interview. The hiring process consisted of 2 technical interviews via phone call and if I passed, I had to go to their office for more face to face interviews. The first interview was basically DWDM fundamentals and a few examples of troubleshooting cases. The second one was supposed to be more detailed. Basically, they asked about types of amplifiers, OTDR, dispersion, transmission schemes (client-network-client). For a first interview, a good theoretical knowledge is a must, and also fast reaction to the practical cases.