There are two types of SIP proxy servers:
1) Stateless proxy server: A simple forwarding function that selects the destination and route of forwarding by requesting information. Messages are discarded as soon as they are forwarded.
2) Stateful proxy server: records incoming requests and sent request information (especially transaction status) and uses this to control future message processing. It also has a fork function for messages.
Provide you with profiles, web addresses of well-known VoIP telephone or phone system providers from all over the world. You can choose different merchants to purchase and your own communication solutions according to your needs.