SIP trunking employs the Session Initiation Protocol to secure a connection between endpoints, which can be almost any device. For example, you can call a colleague on your smartphone, and they can receive the call on their web browser (configured for compatibility).

Your call is routed through a SIP server which manages the connection and signaling. The SIP protocol signals the type of media being transmitted, such as voice or video. Your voice audio is then converted into small data packets and transmitted over the internet or data network to the recipient.

At the recipient’s end, the data packets are converted back into audio. This all happens in microseconds, enabling a conversation with no noticeable delay.

Components of SIP Trunk Systems

The following components make SIP trunking possible:

Session Initiation Protocol

This protocol underpins everything. As mentioned above, it’s the signaling technology that initiates, maintains, and terminates connections.

PBX (Private Branch Exchange)

A PBX is the phone system used to manage internal calls and connect to external numbers. There are three distinct PBX scenarios here:

• Legacy PBX: With legacy hardware, SIP trunking connects your PBX to the internet to facilitate the service. Traditional PBX is rather outdated and requires the most hardware and maintenance.
• On-site IP PBX: On-site IP PBX systems are already set up to leverage internet technology. SIP is connected to enable users in a location to make VoIP calls.
• Virtual IP PBX: A virtual or hosted IP PBX server enables a cloud-based SIP service. This is the best option for scalability and remote working.

SIP trunk

The “trunk” is the virtual connection that links the business’s phone system to the PSTN through the internet. It’s provided by your SIP vendor. 

Internet connection

A stable internet connection is essential to transmit data packets efficiently. Sometimes, companies, especially those with high call volumes, must increase their bandwidth to ensure reliable, high-quality connectivity.

SIP provider

The service provider offers the SIP trunking service, which routes calls to and from the internet, mobile networks, and the PSTN.

What Devices Can Be Connected to Your Company’s Network With Sip Trunking?

SIP trunking supports BYOD (Bring Your Own Device), allowing your team to work on their personal equipment. Compatible devices include:

• Desk phones
• IP phones
• Smartphones
• Desktops
• Laptops
• Tablets

What Costs Are Involved in Sip Services?

SIP trunking is usually charged per user or per minute. For example, $15-$25 per user monthly and $0.015 per minute. Total package costs include:

• An initial setup fee.
• A monthly fee or price per channel, which may include an allowance (a certain number of minutes/calls).
• Call charges (once you exceed your allowance). Charges differ for local, international, mobile, and landline calls.

The maximum number of concurrent calls you expect to make is usually a key factor in determining what you’ll pay. Most services offer flexible pricing, allowing you to match a package to your needs.

Modern SIP trunk services offer several impressive benefits.

Easy Setup and Maintenance

SIP trunk systems are generally easy to set up and manage.

Your provider works with you to manage infrastructure and account setup and configurations. The process typically involves ensuring compatibility with your company’s phone system. Here, you may require updates to your PBX or use a hosted PBX solution provided by your SIP provider.

Hosted SIP trunk services easily integrate with remote offices, usually without infrastructure changes at these sites. With a hosted service, your SIP provider handles all maintenance. In addition to taking care of software updates and security upgrades, they also offer professional guidance, ensuring your trunking arrangement performs optimally.

Cost-Effectiveness

Compared to traditional phone lines, SIP services are very cost-effective. Benefitting from cheaper internet calling, companies can save up to 50% on local calls and even more on international connections.

Maintenance and updates are also included in your subscription, saving you these expenses too.

Plus, SIP providers often bundle in several useful features without extra charge. These may include:

• Voicemail
• Call recording
• Call forwarding
• Interactive Voice Response

Flexibility and Scalability

Hosted SIP protocol systems can scale quickly and affordably. Adding virtual lines is a seamless process, allowing you to onboard new users or multinational locations efficiently and promptly.

Flexible and “elastic” plans often allow you to pay only for the minutes, hardware, and services you use.

You can also scale down if you close offices or consolidate remote teams.

Special Phone Numbers

SIP trunk providers offer virtual numbers in dozens of countries worldwide, including toll-free and local numbers.

• Toll-free numbers encourage more sales calls and present the image of a large, established organization.
• Local numbers help create a local presence and trust in areas where you don’t have a physical office. 

Analytics and Insights

SIP trunk solutions can often integrate apps and functionalities such as analytics, call tracking, and AI tools. This connectivity enables you to gain deeper insights into your customers’ needs, behaviors, call activities, and patterns.

Incorporating these insights with features like call routing and recording helps improve customer service and sales. 

Follow this guide to implement a SIP trunk business phone system in your organization.

1. Evaluate Your Needs

An evaluation of your existing setup is a crucial first step. This should include assessing your hardware and multimedia comms requirements, as well as remote working arrangements. The number of concurrent calls your business makes is also a critical consideration.

2. Compare providers

Compare providers to find solutions that reflect your needs. Key considerations include: 

• Essential features: Such as phone number offerings, analytics and integrations, and routing systems that enhance customer service.
• Compatibility with your existing setup: This will determine what new hardware and software may be required. It also identifies staff skills gaps to inform training plans. 
• Pricing: Look for pricing that aligns with your budget and provides the features you want without bundling in extras you won’t use.

3. Establish Essential Hardware Requirements

Depending on your infrastructure, you may need additional hardware. For example, when connecting a legacy PBX, you need analog telephone adapters (ATA) and a session border controller (SBC) (a gatekeeper between internal and external networks).

4. Install SIP Trunking

With your provider taking the lead, the installation checklist typically includes:

• Setting up SIP trunks
• Registering and assigning phone numbers
• Establishing extensions, routing, and call controls
• Managing APIs and integrations of apps and tools
• Training your team to use the new system’s interface and features