Telephone IP is technology that has been used by big companies for a number of years in private networks. But now, through cheaper equipment and more efficient technology, it is now available to smaller companies.

      Requirements for IP phone calls:

- An IP telephone
- A good connection to a TCP/IP network
- IP-PBX

      At the moment you pick up an IP telephone you will be available to communicate with any TCP/IP user in your network. SIP is a good option; it offers many possibilities and can be used for many years.

      IP-PBX is more than voice on IP. It is a centralized PBX system that uses software, it is able to converge different types of phone systems. It is able to connect with and interact with a variety of telephone technologies such as IVR.

      IP-PBX can function like a switchboard and it can also transfer different types of technology such as VoIP like SIP, MGCP and H.323. Similarly, it can function as a base for using advanced telephone technologies such as, IVR, PBX. Phone conferences, videoconferences, IP-PBX also offers typical phone applications such as grand central PBX, voicemail, phone conferences,  call waiting, call forwarding and call log.

      IP-PBX sends calls and does many other functions of IP telephone. The fact that you are using an IP telephone does not mean that your calls are limited to IP telephones. But rather you will be able to use regular services using PSTN network or an ISDN (TELMEX), analog or digital lines (E1). In fact, the IP-PBX is able to connect to the phone network and install a gateway card in a pc.