SIP stands for Session Initiated Protocol and it has been around for decades. It started out as a way for developers to have a system that keeps people connected over the internet. 

To learn more about SIP trunking and calling, how it’s related to VoIP,  how secure the system is, the trends, and more, check out this post. 

SIP VoIP Phone

What is SIP (Session Initiated Protocol)?

SIP trunking refers to a service over the internet that enables people to have voice calls without the need for an actual physical connection with a phone company or multiple phone lines. People often get muddled between SIP and VoIP because, initially, they seem similar. 

However, VoIP is a term used to define communications using technology in a more broad way. SIP is a specific technology that’s part of the larger VoIP communications services. Where a SIP trunk is installed virtually over your high speed Internet connection.

Developers of VoIP tech often implement SIP as an important protocol when creating communications systems. While it can be very useful for developers, it can also be something that attracts hackers.

What is the Purpose of SIP in VoIP?

SIP is one of the main features used that deals with video and voice calls. Therefore, it’s an integral element that allows VoIP systems to function properly.


Call terminations, message definition between endpoints, establishment of communications, and more, is handled by SIP. Businesses interested in a communications system that’s completely inclusive will benefit from implementing SIP into their VoIP systems.

What is SIP Trunking and How Does It Work?

SIP trunking is program that governs voice communications to one area that’s centralized. It works as a way to broker the connection between your internet connection and phone systems. Most of the time, this connection is established via the internet.

SIP trunks can be purchased from an Internet Telephony Service Provider (ITSP) where they can make the connection to your VoIP system.

What is SIP Calling?

The traditional way of using phone lines involved using the PBX system and PRI lines which lets you have your calls connected with the Public Switched Telephone Network (PSTN). The PSTN is the place where your calls would get routed to the correct location.

When it comes to SIP calling, you’re no longer required to have an association with a phone company. SIP trunking removes the need for PSTN and PRI lines by allowing you to have communications through the internet.

What is SIP ALG?

SIP ALG refers to Application Layer Gateway. It’s something that’s found in most routers that you can find in commercial areas. It’s function is to avoid issues that arise due to firewalls. It does this by investigating VoIP traffic and even altering it in some instances.


By default, a lot of routers have SIP ALG turned on. It’s common for SIP ALG to cause more problems, regardless of its good intentions. SIP packets can be changed in ways that you weren’t expecting, which can lead to them being corrupted. As a result, phone calls coming in can be affected negatively.

If your business is experiencing problems with incoming calls, we recommend checking the state of the SIP ALG. If it’s on, turn it off and monitor any improvements.

What Is A SIP Phone?

SIP phones are similar to VoIP phones and enable your Internet phone service provider to integrate VoIP calling and other UCASS and CPASS features via your Internet connection. There are also software based SIP phones that exist in the cloud allowing you to make phone calls without the need for an actual phone.

What is SIP Used for?

Integrating SIP into your phone systems can provide the business with many benefits. Learn more about why SIP is used below:

  • Lets you know when users are available
  • Provides location details on users
  • Governs media features
  • Can be used for better instant messaging
  • Makes emergency calls easier

Who Are the Top SIP Trunk Providers?

The best SIP providers include many of the common names you’re use to hearing in the business VoIP sector but also some lesser know providers. Common big name providers include both Vonage Business and Nextiva while other less commonly know providers that offer great SIP trunking service include twilio, plivo, MegaPath and Digium. Well know companies for mobile and residential service that provide great trunking service include Verizon and AT&T.

SIP Trunking Prices

SIP trunking pricing is a more affordable way of managing communications in your business. There are a range of pricing plans available, which provides businesses with plenty of flexibility. Check out what the SIP trunking costs are below:

  • Subscription – Can be paid by the DID number or number of SIP channels you have
  • Rates – There are rates for either each phone call or each minute on the line for calls that are outbound
  • Setup – A one-time cost that some providers may not charge you for
  • Add Ons – This includes features such as recording calls for an additional price

In the US and Canada, SIP trunking prices can vary. Each SIP channel has been found to cost an averages of $1.67 to $15 each month. For unlimited SIP trunk channels, the rate is higher and ranges from $19.99 and $29.99 per month.

A Word About SIP Security 

Statistics revealed that 51% of the security issues among companies involve VoIP. One of the reasons for this is because SIP is a protocol that’s internal and external, which can make the system more prone to hacks. 

Some of the most common concerns that businesses have when it comes to SIP is whether hackers can steal people’s identities. Furthermore, some businesses worry about hackers tracing calls or listening in. 

However, many businesses make the common mistake of not properly password protecting their protocols. Often times, passwords will be too simple and easier to hack. It’s understandable, due to how many passwords there are for you to remember.

Changing passwords can also be a process that some SIP systems don’t make as easy as it could be. 

Some of the main ways that hackers can make their way into SIP systems include the following:

  • DOS – Denial of Service can be used to bring down larger corporations who are completely reliant on their phone systems to carry out business. It’s usually achieved by causing tons of calls being made from automated software over long periods of time.
  • SOIP – This stands for Spam Over Internet Telephony which hackers can use to cause automated calls to be sent out in superabundance. 
  • Caller ID Spoofing – Hackers use this method to alter systems so that the number that comes up is different to the one they’re actually using. This can lead to them finding information without being tracked as easily. 

How to Secure Your SIP Phone Systems?

First of all, you’ll want to make sure that the passwords you use for everything are very strong. This includes everything from endpoints to servers. 

A session border controller would be another viable security option. It works similarly to virus protection programs by having more control over the phone calls being made and received by your business. 

Lastly, it may be a good idea to implement encryption. This is because when you make calls using VoIP systems, they aren’t encrypted across the internet. As a result, hackers are able to have a much easier time gaining access to your calls and gaining information. 

It’s best to have the encryption installed for both external and internal communications with the business.

SIP Trunking Trends

SIP trunking refers to the methods that businesses can use to enhance their communications. These methods are also something that can help to keep costs down. 

Learn what some of the top SIP trunking trends are below.

Connecting Link Sites

SIP trunking is the element that keeps your communications service provider and your business in connection. It also involves the unified communications and service providing you with SIP trunking services being connected through an IP.

A session border control is often used to set up this connection. This is to ensure that the connection remains secure. 

SIP Trunking & The Cloud

When businesses make the move to unified communications by using VoIP solutions, they will often use a single platform. This platform is usually centralised and can be used with private cloud systems. 

SIP trunks are provided with the ability to connect sites with the centralized data system. It’s one of the biggest reasons as to why businesses have been able to make the easy switch to VoIP communications. 

Reduced Costs

Traffic and access costs can be reduced when you include SIP trunking practices into your business. These savings will vary depending on the way that you have the communications aspect setup before you make changes. 

You’re also able to have all of your billing available in one easy-to-access place. This can make it easier to manage invoices and costs.

Why SIP Trunking is on the Increase?

One of the most notable reasons as to why SIP trunking has been becoming more popular is because it’s a more flexible model. 

Many businesses like paying a flat fee each month for the communications services as it lets them know exactly where they stand, financially, every month. 

You’re able to see all of the monthly costs for your unified communications in one place. Moreover, you can have calls set up as a whole for the business, rather than having to create plans for employees individually. 

Providers of SIP trunking have put more of an emphasis on voice traffic. As a result, the dropped call rates can be decreased and companies have been noticing that the audio quality is an aspect that has improved.

Sip Trunking Pros & Cons


Multiple Locations

SIP trunking can be very useful if there are multiple locations that your business runs from. This is because it’s a system that’s central and over a network that’s private. 

You’re able to have an easier time keeping control of your communications and save money on using one system. 

Same Rates

Regardless of where you make your calls to, you’ll be charged the agreed rate. Therefore, there are no limitations that cause you to have to pay more. 

Advanced Tech

You have the benefit of using the most up-to-date technology which can continue being upgraded. 

SIP trunking also allows you to make calls very quickly. As a result, you can run your business more efficiently. Not to mention, it helps you to not use as much of your bandwidth since calls go through faster. 


One Platform

While having one SIP trunking platform can make things a lot more simple, it also means that you rely heavily on it. Therefore, if there are issues, your communications could be completely down until it’s resolved. 

Therefore, some businesses make sure to keep their PBX systems to use as a secondary form of communication. 


As we’ve covered in this post, security could be a major issue when implementing SIP trunking. This goes back to having one platform that all of your information and voice calls go through.It can leave the system more open to hackers finding sensitive information about the business or an injection of ransom or extortionware. Therefore, you’ll want to make sure that you don’t skimp on having reliable protocols in place to prevent hijacks. 


SIP trunking services may not always provide you with an E911 or 911 service. This is something that’s crucial for you to find out beforehand. 

If not, emergency services may not be able to discover your location if something happens. This is more so a problem for businesses that create their own SIP trunking or have it outsourced with providers of VoIP services.

Having said that, it’s now more common for services providing SIP trunking to have an E911 feature. 

PBX Systems

Some businesses have been surprised to find that some SIP trunking providers will need you to use PBX phones. 

This may be more of an issue when it comes to integrating the system to elevators or machines that are older.


If you were interested in integrating SIP trunking as a part of your business, you can use the info found in this post to help you feel more confident about the different aspects to consider.

There are pros and cons to the service. However, with the rate at which technology is advancing, it looks like SIP trunking services are going to continue improving. This is especially since so many businesses have been turning to VoIP service providers to help their communications run smoothly. 

Hopefully, we’ve helped you to learn more about SIP trunking to make the best choice as to whether it’s right for your business. 

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