SIP Trunking is a cloud VoIP solution used to deliver phone lines to an IP PBX or any kind of VoIP or SIP-capable business phone system or gateway. It enables organizations to connect their PBX (Private Branch Exchange) to the public switched telephone network (PSTN) via a broadband internet connection.

To understand it better, SIP Trunking is an application layer protocol that helps establish voice and video sessions between devices or applications through the internet, unlike a traditional phone line, which relies on fixed connections through Telco to communicate.

SIP Trunking Buyer’s Guide

SIP Trunking services are increasingly popular in companies because they are more flexible, feature-rich, and less expensive than traditional landlines. Its popularity in the market has also led to a greater number of suppliers in the market. The experts in cloud phone systems at RingOffice have prepared this buyer’s guide for all people who do not know what to look for in SIP-Trunking service providers.

Quality of Service (QoS)

The first point of contact between customers and your business is the phone. The poor audio quality or busy tones due to insufficient capacity reflect poorly on your business. Look for a provider that offers Quality of Service (QoS) guarantees, with features like prioritization of voice traffic over data, and tools to monitor and optimize call quality. Here are some things to look out for when choosing your SIP Trunking service provider:


Some providers of SIP Trunking services do not have their own infrastructure and depend on a third party to troubleshoot and solve problems.

Number portability

Make sure your provider can transfer all your existing numbers so that you do not end up with multiple providers and multiple bills.


Not all providers are equipped to handle global traffic well. Make sure your provider is able to offer premium quality routes that can handle all your call traffic with business-class quality.


Having a knowledgeable support team to assist in a timely manner is priceless when you run into a problem that affects your business operations.


Make sure that the provider offers reliable service with high uptime guarantees. Ensure that they have multiple data centers in different locations to ensure redundancy and continuity in case of failure.


SIP Trunks are exposed to cyber-attacks by hackers just like any other device that connects to the internet. Some providers do not have anti-fraud systems. Anti-fraud systems can help protect you from the excessive costs of fraudulent calls caused by cyber-attacks. Look for a provider that offers secure SIP trunking, with encryption and authentication features to protect your data and communications. They should also have robust measures in place to prevent fraud and unauthorized access.


A major benefit of SIP Trunks is flexibility. SIP trunking allows you to share channel capacity across many phone numbers and even locations globally. It can also give you the ability to scale up and down your channel capacity as needed. They are also easy to configure and move whenever needed. All of these benefits result in tremendous convenience, dynamic calling capacity, and cost savings.


Ensure that the provider can scale up or down the service as per your business needs. Check if they can accommodate seasonal fluctuations in call volume or sudden spikes in demand.


A great feature of SIP-Trunks is Burstability. Some providers allow you flexible capacity so you can overflow your channel limit when needed. This comes in handy on busy days and helps avoid customers from hearing busy tones on days when your business is busy.


As opposed to traditional landlines, SIP trunks are very easy to configure and manage. There is no need to send a technician to your office when setting up a SIP-Trunk or adding channels. Features can also easily be managed online so you never have to wait days or weeks to implement changes.


SIP-Trunks should allow you full control of call flows in a failover scenario. Features like failover forwarding, failover voicemail, and time-of-day-based call flow rules can make managing your incoming call flow very easy in the event of a site outage.

Coverage and Compliance

You must ensure that the provider offers coverage in the regions where your business operates, with local phone numbers and support for international calling. Also check if the provider complies with regulatory requirements, such as E911, number portability, and data retention laws.


If your business has already made the investment to buy communication equipment, find a provider that offers a compatible service with standard SIP-based VoIP phone systems and gateways and not the other way around.

If you are looking for your company to change from traditional landlines to Cloud Communication or Trunking technology, make sure you understand the benefits of the devices and choose a SIP Trunk service provider that is reliable, prioritizes quality, and gives you flexibility and control to manage your communication service as needed.

If you are still not sure which service is right for you or have questions about SIP Trunking services after going through this buyer’s guide, do not hesitate to contact the RingOffice experts. We are here to answer your questions and help you design a solution that best suits your business needs.