What is an SIP Proxy Server?
What is an SIP Proxy Server?
What is SIP?
You’ve probably heard of VoIP, or Voice Over Internet Protocol. It’s also known as Internet phone or broadband phone service. VoIP lets you make and receive phone calls using the Internet. Some popular VoIP providers include Nextiva, Vonage, and Google Talk.
VoIP uses what’s called protocols, or sets of rules and requirements for sending and receiving information through a VoIP service. Developers use protocols when building VoIP devices so that different devices can communicate with each other in the same digital language.
One of these VoIP protocols is called SIP, or Session Initiation Protocol. SIP is one of the most popular VoIP protocols for businesses, and it’s now becoming an industry standard. SIP allows businesses to communicate through phone calls, video calls, and instant messages over the Internet. SIP can even be used to securely send documents, images, and other files over the Internet. Popular SIP clients, or software programs for SIP service, are XLite, MicroSIP, OnSIP, and Ekiga. Many VoIP providers also provide SIP service.
How does SIP work?
One of the reasons why SIP is so popular is because of its low cost and the freedom it provides. SIP can be used worldwide without being restricted by laws and charges. All you need is a high-speed Internet connection, an SIP client, and an SIP address, which is sort of like an email address that identifies you to other SIP users. An SIP address is formatted like an email address with a username, the @ symbol, and a domain name (e.g. “firstname.lastname@example.org”). You can create your SIP address through your SIP client when you set up your account, usually for free.
You can set up multiple SIP addresses on a SIP network. An SIP network is a group of devices that are connected through the same SIP service. These devices can include phones and computers, and they can be in the same room or office, in the same building, or even spread out in different parts of the world. As long as all of the devices are connected to the Internet, they can be part of the same SIP network.
Hard phone or soft phone?
Once you have your SIP client and SIP address set up, you can connect either a hard phone or soft phone to your SIP service. A hard phone is like a landline handset phone that sits on your desk or hangs on the wall. It’s called a “hard” phone because it uses hardware. A hard phone is always connected and always ready to send and receive calls.
One benefit of using a hard phone is that it doesn’t depend on a computer or other device to connect. A hard phone plugs directly into a router or access point, so your computer doesn’t have to be turned on for your SIP phone to work, and you don’t have to worry about other programs on your computer slowing down or interrupting your connection. A hard phone can also connect wirelessly through a Wi-Fi network.
A soft phone is a software program that connects to the SIP network. It’s called a “soft” phone because it uses software to connect to your SIP service. Your computer must be turned on and your SIP client must be open in order for your soft phone to make and receive calls. A soft phone also requires audio hardware. For phone calls, you’ll need headphones or speakers and a microphone or headset with a built-in microphone. For video calls, you’ll also need a webcam.
The advantage of using a soft phone is that it can be used to not only make phone calls but also make video calls and send instant messages and files through the SIP network. The disadvantage is that other programs on your computer can use up your processor and slow down or interrupt your SIP connection. Also, if your computer is down, your SIP service is down, too.
What is an SIP proxy server?
An SIP proxy server is a computer or server that transmits information from one SIP device on the network to another, kind of like a router or gateway. When you make an SIP call, it is first sent to the SIP proxy server. The SIP proxy server finds the address of the SIP device you’re calling, connects your device to that device, then drops out of the connection.
Think of a SIP proxy server as an old-fashioned phone operator. You pick up your phone, tell the operator who you want to call, and the operator connects you. An SIP proxy server works in much the same way.
Stateless or Stateful?
There are two types of SIP proxy servers: stateless and stateful. A stateless SIP proxy server simply receives and transmits information without doing anything else with it. When you make a call, a stateless SIP proxy server connects your call, and that’s it. Once a call or message is transmitted, the information is forgotten. Because of their simplicity, stateless SIP proxy servers tend to be faster and more efficient than stateful SIP proxy servers.
A stateful SIP proxy server doesn’t simply transmit information; it also stores the information being transmitted so that it can be accessed again later. Whether you’re making a call, sending an instant message, or sending a file, it’s all saved on a stateful SIP proxy server. One advantage to using a stateful SIP proxy server is that if the connection doesn’t go through the first time, a stateful SIP proxy server can re-send your call or message until it’s successful. Because they take the time to save all of the information being transmitted, stateful SIP proxy servers tend to work a little slower than stateless SIP proxy servers.
Why use an SIP proxy server?
Every SIP network needs an SIP proxy server to make sure it runs smoothly and securely. An SIP proxy server can provide network security, call forwarding options, and the option to save information from calls and messages.
- Network Security: An SIP proxy server can confirm a caller’s identity to make sure they’re authorized to connect to the SIP network. This prevents hackers and other unauthorized users from making or receiving calls or sending instant messages or files. An SIP proxy server can also be used to prevent authorized users from making unauthorized calls or calls outside of the SIP network. When a call requires a charge, the SIP proxy server can check the user’s credit to cover the cost of the call. If the user doesn’t have enough credit to make the call, the call will be disconnected.
- Call Forwarding: An SIP proxy server can be used to forward calls to multiple SIP devices. When a call comes in, the SIP proxy server can make the call ring on multiple phones at the same time. Or it can send the call through a sequential list of phones, ringing one at a time until the call is answered. You can program the SIP proxy server to ring a certain number of times on each phone before it moves on to the next phone. If no one answers the call at any of the phones, the SIP proxy server can forward the call to a voicemail system. An SIP proxy server can also be set up to follow a set of call forwarding rules to route calls to different departments or devices.
- Saving Information: A stateful SIP proxy server can make sure that your messages, calls, and files are saved as they’re being sent and received, so you can access them later or re-send them when they don’t go through. This can help you keep track of your important calls and messages.