Opensignalmaps is a free web service that will provide the details of cell phone towers, cell phone signal strength readings and Wi-Fi access points around the world. The site claims that they collect the data from purely objective signal & tower location data. The data is completely anonymous and they do not track personal details such as name, email, passwords etc. No sign up or download is required for using it.
Opensignalmaps provide a map for finding the signal to view signals, simply go to opensignalmaps website select your area. It will provide details service providers of that area. You can also select 2G, 3G and 4G networks.