The most popular satellite phone is the handheld units. It can be very difficult to get a signal with a handheld satellite phone while indoors. The structure of the building blocks the signal. You must have line-of-site to one of the satellites the phone uses to receive a signal. As a rule, when using a handheld satellite phone you must be outside away from large structures and trees to receive good service.
If you require satellite phone service inside a building you can place an external antenna outside the building. The antenna would need to have at least 80% view of the sky if not more. The antenna must be away from other antennas and anything else that might interfere with the antenna receiving a signal.
Most handheld units have accessories that allow them to be connected to an external antenna designed for buildings or vehicles. Once connected to this external antenna the satellite phone would have line-of-site to a satellite.
If there is no need for the portability of a handheld satellite phone then most satellite phone providers offer Fixed Site Satellite phone units. These Fixed Site Satellite phones come with external antennas and are designed to be used in a building or in some cases vehicles. Most Fixed Site Satellite phones come with a RJ11 standard phone connection. You can either plug in a standard analog corded or cordless phone into the unit which will provide a dial tone just like you have at home. This makes the use of the phone very simple with little to no training required. A Fixed Site Satellite phone can also be connected to an analog connection that is provided on most PBX systems allowing emergency use of the satellite phone in the case of an emergency.
Most Fixed Site Satellite phones are single circuit phone systems meaning they can only provide one phone line. If multiple phone lines are require you will need to purchase a Fixed Site Satellite phone for every phone line required.