Voice over IP (VoIP) is a technology that allows telephone calls to be made over computer networks like the Internet. VoIP converts analog voice signals into digital data packets and supports real-time two-way transmission of conversations using Internet Protocol.
When you call your office from your traditional home phone, a regular PSTN (Public Switched Telephone Network) is used. So your phone is connected to a telephone switch by a pair of copper wires. Such calls occupy a physical channel exclusively. Also the phone installation fee may be quite expensive if you need to lay a cable between a telephone switch and your office or apartment.
Unlike a traditional telephony, VoIP uses very cheap and easy accessible Internet network as voice transport:
Benefits of VoIP telephony:
- cheap calls (usually free between two VoIP parties)
- mobility: you may call and receive incoming calls with your IP-phone application installed on your notebook even if you are travelling, while with a traditional telephony you are bounded to a copper pair connection to a telephony switch
- number portability: no need to change your phone number for incoming calls if you decide to change your geographical office location
- no capacity limits – amount of simultaneous calls are limited by your Internet connection bandwidth
- lots of extra telephony services may be easily implemented over your VoIP connection (conferencing, video calls, IVR, voice mail, follow-me service etc.)
Usually end-point calling parties use service by VoIP providers. The companies provide their customers with call routing to PSTN/GSM networks and lots of extra services.
Let’s see how we can terminate VoIP calls to GSM networks.