What Is SIP Proxy Server?
SIP Proxy Server, or sometimes called SIP Proxy or SIP Server, acts like intermediary or facilitator among SIP devices assisting point-to-point communication from picking up to dropping of calls. However, SIP Proxy’s job is more than just a go-between.
To make it easier to understand, we can think of SIP Proxy Server as a phone call manager and security guard. Now, let’s learn what its duty is in each role.
Phone Call Manager
- Assist call processing in the SIP network to set up calls between SIP devices and implement provider call-routing policies.
- Control call rules such as arranging simultaneous or sequential phone rings and the time length before the call being transferred to another destination like voice mailbox or another extension.
- In some circumstance, a SIP Proxy Server even interprets or rewrites certain parts of the request messages before forwarding them.
Security Guard
- Grant or deny access to a network resource. A SIP Proxy Server first ensures that a user is the correct person and then based on that, it determines the user’s identity and authorizes the user to access various resources.
- Enhance network security. For example: A SIP Proxy Server checks the caller’s identity and credit before the caller can connect to a destination that costs money such as PSTN network or foreign locations.
Two Types of SIP Proxy Servers
Based on how the SIP Proxy Servers handle the information they receive, there are two main types of SIP Proxy Server performing different functions to fit users’ needs in different situations.
Stateless Proxy Server
Stateless Proxy Servers simply pass along the messages they receive to the assigned destination. They don’t store any information of the call and transaction.
Since they don’t need to spend the extra time and energy to remember the SIP requests and messages that they have forwarded, Stateless Proxy Servers usually work very fast and efficient. Therefore, Stateless Proxy Server works well for network hubs.
Stateful Proxy Server
Stateful Proxy Servers, on the other hand, track everything from SIP requests, messages, to responses. This function allows you to restore the information you need in the future and also retransmit the request if the servers haven’t received a response they were waiting for.
More Questions?
Do you have more questions about SIP Proxy Servers? Please utilize the comment box below or give our VoIP experts a call today at (866) 582-8591 or email at [email protected]. We will be thrilled to hear from you and happy to assist you with any VoIP questions.
2 Comments
Can a SIP PROXY provide VoIP survivability for an enterprise? How would that work?
Hi Glendon,
Thank you for your question! Please see the answer below from our VoIP expert:
Survivability is your VoIP key asset when using a Proxy!
When using a SIP PROXY, this will offer a high-security measure and also device support enhancements. Using both TCP/UDP protocols will support a wider range of the device. The Proxy will provide TCP to UDP bridging in all aspects. There are 3 versions of SIP proxies, 1.0, 2.0 and 3.0. The first will provide proxy and registration functionality, remote management and an unlimited number of routing destinations. Both protocols will use the authentication process on the IP PBX server and also will include a sense of load balancing.
In short, when you go to register a SIP device, you are asked for a “SIP SERVER IP ADDRESS”, in turn, you can use the PROXY server address as well. The proxy was specifically designed for VoIP!
If you have more questions, please don’t hesitate to reach out to us here!
Thank you,
Evy