There are two basic types of internet telephone. The second type of internet telephone allows users to make calls within the confines of the internet. But calls made on this type of telephone cannot be rerouted into the old telephone system. Despite this restriction many people and companies are now using computer to computer internet and intranet communication. It requires that the recipient and the caller have compatible systems, but then so did the old telephone system.
Gateways are the key to bringing Internet telephony into the mainstream.
Gateways also overcome another significant Internet telephony problem, addressing. To address a remote user with a gateway product, you only need to know the user's phone number. Internet telephony gateways combine voice and data on one network, hence offering a range of applications. It can now be hooked up to our computer by means of an interface that has a phone jack. This gives additional offshore telephone flexibility.