It is a device capturing and controling all the signals, which are being created by the whole system, especially the made and received phone call signals. The device is mostly used for connecting regular phone system with the Internet and backwards.
We are all human and therefore we all need to rest. Foreign countries attract people, because "the grass is always greener at neighbors’ yard." But while abroad, we also want to keep in touch with family and friends in order to tell any news or just share experiences.