I am facing mobile network issue in my office only. When I enter in my office my mobile signal problem arises, Is it due to the router or some other electronic devices? And when I go out from my office I again got signal into my mobile what exactly the issue is. I am not getting.
If I understand correctly, you are facing signal loss when inside a building?
If so then that is normal. Indoor areas suffer from lower signal reception due to the having to pass through the walls. Whilst modern signal transmitters and phones are usually only marginally affected, all sorts of factors can affect this including how "deep" into a building you are, distance from transmitter, building materials etc.
If you are only facing this issue inside a particular room then perhaps the room is specially screened? You may also be in a signal dead-spot where you just have little signal.
Whilst WiFi and other common wireless systems are on frequencies that should not interfere with your phone signal, you may have some specialist kit in your office however this is very unlikely.
If you'd like to track your signal strength as you move between locations you can use the phone status option in settings.