SIP telephony

About SIP telephony

SIP stands for Session Initiated Protocol which is a protocol developed by IETF – The biggest technical management for internet. This protocol allows media and sound to be transported over internet. SIP is especially known its benefits in telephony and video call. SIP telephony exists in a range of differents types and versions.

What is SIP telephony?

SIP telephony in essence means that you can call through your internet subscription. For a company this means that you have both your internet connection and telephony system via the same supplier. In that way you get an unlimited amount of lines in your PBX which in turn has a lot of benefits.

Calling is cheaper for a company with SIP telephony both nationally, internationally and to mobile phones. From a cost perspective it’s highly beneficial. Another benefit is that the company’s communication increasingly becomes more mobile, everyone can work as long as there’s an internet connection, whether you’re abroad or at your summer rental.

  • Lower costs for fixed telephony in all offices.
  • Minimizes the amount of fixed subscriptions for company telephony.
  • Only one PBX function for all offices in the company.
  • All communication is conducted over the same network.
  • Increased security with the ability to block certain countries or regions.
  • SIP telephony provides a better overview and and in turn better customer service.
  • Gives companies increased mobility due to that the only thing required is access to internet.

SIP creates the opportunity to establish sessions between two parties, the recipient and the sender, by notifying the recipient of the incoming session. With SIP telephony, you can also park calls, divert calls and add media streams or change media coding. You can also add new participants during the session.

This technical standard has a lot of similarities with http when the messages have headings with information with associated message body. The appearance of the message is then determined by the SDP. SDP stands for Session Description Protocol.


How does SIP work?

Let’s imagine a scenario where a person is calling from their computer with a SIP-client to the company with SIP-telephony.

  1. During the call, the special software (codec) compresses the clients’ voice into digital signals.
  2. The signal is transferred to the unit (computer, SIP-phone, etc).
  3. Two units find each other with IP-address and start the communication session.
  4. The signal decompresses and the person can hear the clients’ voice.


What are the requirements for SIP telephony?

To call with SIP telephony you need an IP telephony or VOIP telephony installed. This is easy delivered throuh your internet provider. There are a few variations of SIP telephony; either a program baed SIP phone, a USB VOIP phone or a machine SIP phone.

A program based SIP phone is simply a program that is installed on the computer. It uses the computers’s microphone and speaker to call. Alternatively you can connect a headset when calling a program based SIP telephone. A USB VOIP phone is connected to the computer’s USB port which is used as a normal phone.

The last alternative is a machine SIP phone and it looks and is used just like a regular phone. The only difference is that it’s connected directly to the data network and also has an integrated mini hub så that the phone can share the network’s connection with the computer. Thanks to the mini hub it doesn’t require an extra network spot for the phone.

SIP telephony benefits

Leading business developers within IP telephony are unanimous that SIP telephony is the future. Most of the knowledgeable in the field see SIP as the standard that will be in the forefront when it comes to communication over internet. Even today there are countless benefits and we can only speculate what the future will bring.

A great asset with SIP for companies is that you can have many users in one session. That means that you can call a contact for a video call and then include more if needed. You can also call another mobile phone and only choose voice to that person.

 With SIP you can easily manage IP telephony, video conferences, direct messages and fax over internet. This is also meaningful for the company’s PBX due the the fact that it provides better insight in employee’s statuses. You can easily see who’s busy in a call or in phone meeting which gives better customer service.

Standardization of SIP

Version 2.0 of SIP was standardized in 2002 and has since expanded and changed a lot. A new framework has therefore emerged under the RFC documents. Now more emphasis is placed on using TCP for communication. SIP outbound has been created to strengthen signaling towards the recipients.

SIP telephony and security

There are many security features around the SIP standard and for those of you who are a bit more technically familiar, here are some of the SIP phone’s security features. For authentication, HTTP MD5 and SHA256 digest authentication are used. TLS is used to hide communication between devices. TLS stands for Transport Layer Security and is a cryptographic communication protocol, an open standard for securely exchanging encrypted data between different computer systems. However, TLS does not hide the information from the servers that handle the calls. S/MIME is a standard for email encryption and is also used in the SIP telephony. That standard provides SIP with secure identities between two domains. In addition, this standard provides privacy protection for messages via SIP.

What is the difference between SIP and VoIP?

VoIP is used to make calls over Internet or internal networks. SIP, on the other hand, is an application protocol used to establish, modify and terminate multimedia sessions such as VoIP calls. The big difference is simply what they intend to do. VoIP is not a discreet technology in itself but is instead a family of several different technologies in modern telecommunications networks. SIP is a signaling protocol that falls under the VoIP umbrella.

Another difference is that VoIP sends voice messages, while SIP can carry all types of media, and thus not just voice. Data is sent via SIP trunks in packets, which can include voice, data or video. This means that SIP systems allow users to make voice and video calls online.

In terms of units they also differ. VoIP phones must be connected to a computer to call, and that computer needs to be turned on. With SIP phones you don’t need a computer and it only requires a modem to work. This means that the SIP phones are more like traditional phones in the sense that they work independently.

VoIP hosts also handle traffic differently from SIP systems. SIP systems are processed through individual systems located in each user’s system (also called user agents). This type of peer-to-peer system can handle large amounts of data and traffic because they have access to more bandwidth and resources. VoIP hosts hand, filter, organize and direct traffic through a central network. In this type of system, large amounts of traffic can overload the system, thereby affecting overall performance. An advantage of VoIP is that fewer communication points means higher security. But one advantage SIP has is its ability to interact intellectually with other protocols. It can customize signaling protocols to match the client’s. It is also fast, flexible and scalable to meet specific needs.

What Soluno offers

We at Soluno can help your company with cloud-based PBX solutions where your calls are transmitted over the internet. Want to see a short video demo of what our services look like? Click the button below.


Latest update Nov 2020