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What are SIP trunks and why do you need them?

Many of the services we provide are crystal clear to us, but they can be rather vague if you’re not active in the (customer service) inbound and outbound voice industry. So, let’s explain some of those terms, starting off with SIP trunks.

What are sip trunks and why do you need them

What are SIP trunks

SIP trunks enable you to initiate, manage and end audio and/or video connections with VoIP (Voice over IP). It sounds like it’s a product that comes out of a box, but it’s not. It’s a digital product and merely a set of common and widely used internet protocols that can be used to facilitate in- and outbound telephony traffic. They are the digital equivalent of traditional analog phone lines.

How does SIP trunking work

With SIP trunking you can make local, national, and international phone calls over the internet. Any global customer service number can be connected, and calls can be delivered wherever you like. SIP trunks can be connected to an on-premise PBX and to a hosted PBX (in the cloud). They can act as a bridge between a traditional phone line (PSTN) and VoIP and turn the traditional analogue phone call into a VoIP call.

What are the benefits

SIP trunking is becoming increasingly popular as carriers are gradually phasing out the traditional phones lines of the Public Switched Telephone Network (PSTN) and moving to IP. Installing SIP trunks will make sure you’re set up for the future. And that comes with a lot of benefits:

  • No costly hardware investments
    All it takes is connecting your current voice network to the internet
  • Save costs
    Benefit from lower monthly rates and lower call charges
  • Increased flexibility
    No longer be restricted by number of lines or concurrent calls. Easily adjust things like routing and endpoints
  • Increased scalability
    Quickly set up and connect new geographic locations as SIP trunks can be scaled up and down around the globe
  • Increase quality and reliability
    Calls are routed over the internet as VoIP, so you can gather, monitor, and act upon a lot of data. This increases the quality and reliability of the connection
What are sip trunks why do you need them

Who should consider SIP trunking and why

SIP trunking is especially interesting if you:

  • still use traditional phone lines for inbound and outbound calls
  • still use an analogue PBX
  • handle high volumes of long-distance or international calls
  • want to be more flexible when it comes to scaling up internationally and no longer be dependent on a geographic location

Switching to SIP trunks will help you take advantage of the previously mentioned benefits like lower costs, increase the flexibility and scalability of your company as well as the quality and reliability of your connections.

How to choose a provider

Since SIP trunking is booming business, there are many providers around. And they don’t all provide the same quality. When choosing a provider, consider these important items:

  • price: make sure you know the price of all factors involved. Not just the obvious ones like set-up and monthly costs but also the number of sip channels included and traffic costs for toll-free and international calls
  • support and reliability: check out the company’s track record, support and uptimes and find out what their monitoring policy looks like
  • security: does the provider simply use public internet, or do they also provide more private connections like VPN, MPLS, or DSL. Can they automatically block destinations that are often used in fraud or scams for outbound traffic
  • number porting: can the provider port your existing phone numbers in any region of the world
  • supported features: what other features are supported like for example SIP-registration, IP-whitelisting, IPSec tunnels and network integration.

How to install and deploy

Installing and deploying SIP trunks is easy. The exact process depends on a few variables like your business goal and what business phone system you use. If you want to switch to a Sound of Data SIP trunk, we’ll do the installing and deploying for you or help you through the process.

What are sip trunks why need them

How much do SIP trunks cost

The pricing of a SIP trunk varies per provider. The Sound of Data platform handles aggregated high volumes of all customers and combines multiple carriers. This means we have a procurement position you can’t obtain on your own. Switching to a Sound of Data SIP trunk lets you take advantage from that benefit. If you want to know more, download our Product Paper, or contact us for more information.


  • SIP trunks vs SIP channels
    A SIP channel is the virtual line for a single call on a SIP trunk. You need a channel for each of the simultaneous calls you make. Adding new channels is done virtually. There’s basically no limit to the number of channels on a trunk. But they do need to be added before they can be used. SIP channels are also referred to as SIP trunk channels or SIP lines.
  • SIP vs. VoIP
    SIP and VoIP are both common internet protocols. VoIP (Voice over Internet Protocol) is used to make and receive phone calls or video calls over the internet, like with WhatsApp. SIP (Session Initiation Protocol) is a protocol that enables you to initiate, manage and end audio and/or video connections with VoIP.
  • What are the requirements to connect a SIP Trunk?
    The most important requirement is a steady and fast internet connection. You’ll also need an on-premise or hosted (IP) PBX to connect the SIP trunk to as well as phone numbers.
  • How many concurrent calls can be made? And how does it relate to bandwidth?
    The number of concurrent calls depends on the number of SIP channels on the SIP trunk and on the bandwidth of your internet connection. There’s virtually no limit to the number of channels that can be added, so the number of concurrent calls basically depends on the bandwidth of your internet connection.
  • Is there a limit on how many phone numbers I can have?
    No, there is no limit to the number of phone numbers that can be connected to a SIP trunk. And they can be from any location you want.

Explore the benefits

If you want to explore how your business can benefit from using SIP trunking, get in touch. You can schedule a free call in the box below, download the product paper or call us for more information.

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