What is the ruling on working for a telecommunications company that provides services to banks and large corporations, and what is the ruling on working for it specifically with the World Bank?

The basic principle regarding working in telecommunications companies is that it is permissible because it is a means used for both permissible and impermissible things. It is permissible as long as it is not used as a means for something prohibited. If a person is assigned to a service with a prohibited activity, they must refrain from it. As for the bank mentioned, if its activities are permissible, then there is no harm in being seconded to it. However, if it involves usurious loans and the like, then it is not permissible.