| The VoIP carriers have become an ultimate means of | | | | The convergence of the Internet with other allied |
| achieving connectivity or terminating calls with ease. | | | | networks has led to the generation of an infrastructure |
| This works well as the carriers have merged their | | | | that supports the carriers and suppliers of IP telephony |
| services with other higher version network providers. | | | | services more comprehensively. As there are several |
| This has, in a way, resolved the issue of fast | | | | suppliers of origination services, so now the VoIP |
| connectivity at low rates for many users - business or | | | | carriers prefer to have connections that give them the |
| otherwise. | | | | flexibility to switch to different origination services as |
| In general, the VoIP carriers offer their services to the | | | | and when the need arises. |
| resellers. The system follows a three tier rule. Tier 1 | | | | This new capability in VoIP carrier service is achieved |
| carriers offer their services to Tier 2 that in turn | | | | by a Session Internet Protocol (SIP) that is actually |
| enables the functioning of Tier 3. The Tire 1 consists of | | | | another interconnection. This connection provides |
| those companies that come with their physical | | | | unique efficiencies in networking and also maintains |
| network either in one country or in some regions of | | | | flexibility in its design so as to cater to the needs of |
| the world. The carriers at this level can terminate the | | | | different categories of carrier customers. Though SIP |
| voice traffic or can carry forward a call using their | | | | allows the customer to switch to different origination |
| own equipment and expertise. The second is the Tier | | | | services but it is actually based on inbound and |
| 2 that consists of companies that take the network of | | | | outbound call service. That is to say that once an |
| Tier1 on leases it in order to terminate international calls. | | | | inbound call is received, the customers can use the |
| The Tier 3 consists of service providers that make | | | | 'Global Crossing Carrier' or outbound service to send |
| use of Tier 2 or Tier 1 carriers to terminate international | | | | the call back to its destination. So, for a VoIP service |
| calls. | | | | provider, SIP is used as a gateway for telephony, |
| With the introduction of VoIP, several technologies | | | | internet conferencing, events notification and instant |
| have converged so as to enable a more reliable and | | | | messaging. |
| sophisticated service in the realms of communication. | | | | |