Companies like InfoStructure provide open access to their telephony services over the Internet.
Internet Telephony Service Providers (ITSPs) provide SIP trunking services to all who have Internet connectivity. VoIP communications is just another application provided over the Internet alongside Web, e-mail, FTP and other services commonly found on the Internet.
ITSP companies like InfoStructure provide open access to their telephony services over the Internet. The enterprise leases telephony services such as SIP trunking to provide PSTN numbers and access.
The ISP (Internet Service Provider) is simply the service to gain access to the Internet. The physical connection to the Internet can vary according the enterprise’s needs; it can be as small as DSL or grow to T1, T3, Ethernet, OCx, and more. The advantage is the consolidation of both voice and data traffic on the same physical connection, thus maximizing bandwidth utilization and minimizing monthly reoccurring costs.
Firewalls are critical in this deployment, providing voice and data traffic security to the enterprise: solving the NAT traversal issues through the corporate firewall, monitoring and providing security to SIP traffic, and protecting the IP-PBX from malicious attacks.
The downside is that the voice communication is only as good as the Internet connection that is being used because that link is not managed from end to end. The advantages of this type of delivery is that it is available anywhere and typically is offered at very attractive rates. With an Internet connection, afirewall at the edge to resolve routing and security concerns, and a good ITSP, SIP trunking may be delivered anywhere in the world.