What is SIP trunk?

SIP is a signalling protocol which is used for real-time delivery of media and voice. With the accurate interconnections in place and the right infrastructure, SIP calls can be communicated between PSTN and data networks, the global frame of traditional phone networks ran by regional, national and mobile network carriers.

In simple terms, a SIP trunking is used to enable your on-site phone system for making and receiving calls through data connections. A virtual number known as DID (Direct Inward Dialling) can be allocated to your SIP trunk connection so that your customers have a number to call whenever they want to talk to you.

As for the trunks, you can think of them as a phone line in the old parlance, which carries media and voice content among two endpoints, which can be phones or VoIP terminals. The benefit of SIP is that you can get as many channels as you like pointing to a single virtual number. This is one reason why SIP trunks provide considerable cost savings in comparison to traditional telecommunications. Also, there is no need to invest money in costly on-premise infrastructure before employing SIP trunking.

Integrating your telephony service into your data network and managing it in the cloud can also lead to big ROI savings on the existing infrastructure which provides different opportunities to drive cost savings. Now we are going to discuss the benefits which we mentioned before.

The SIP trunks Benefits

Local Presence

Since the phone numbers linked with SIP trunks are virtual, they don’t have to be fixed with your actual physical location, apart from where regional regulations need this. This means that you can use the DID number and SIP trunks for two-way voice services which allows you to conduct business from your office in London, even if you actually do not have an office space in London.

If your SIP trunk provider’s network is completely interconnected with the national telecommunications infrastructure in any given country, you will be able to make local phone calls which are routed in the country, meaning call quality, carrier-grade latency, and privacy. Also, you will have access to the whole national dialling plan in that state, including special phone numbers which cannot be reached by international call services. They will appear as local phone numbers in the caller ID, rather than presenting with international dialling prefix. This is a huge deal since local phone calls are four times more likely to be answered compared to international calls.


SIP trunks can be extremely flexible which allows you to scale your business phone system as your business grows. You can also easily deploy voices services and extra capacity as and whenever you need it, in offices around the world, without ever having to invest in expensive infrastructure.

Unlimited call capacity

SIP trunks also allow you to make unlimited call at the same time, this means that you can enjoy as many simultaneous calls to and from a single phone number as you wish. This particularly is beneficial for customer contact centres which receive dozens, or even hundreds of calls every day to a centralised phone number.

Consolidation of service providers

With traditional phone carriers, you only get coverage in one country meaning that you have to enter into agreements with dozens of providers for an international communications footprint.

This process can be migraine inducing due to the local regulatory needs of every country and the lack of constant procedures across borders. A SIP trunk service provider will be responsible for resolving these issues for you, by communicating with local networks in every country to offer streamlined services around the globe. All that is left for you is to choose a UK toll-free phone number, a Chinese local number and whatever else you require.

Centralised comms

If you have different business locations then the SIP trunks can remove the need to individual phone lines at every location, consolidating all offices or branches and making a single and centralised platform. This results in decreased hardware needs and an impressive long-term cost savings. Keep in mind that to completely replicate the functionality of the PSTN for business, you will require a SIP provider which offers:

  • Outbound voice (domestic and international)
  • Number portability
  • Inbound voice
  • Access to local emergency services numbers

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Mila Jones

Mila Jones is a farmer of words in the field of creativity. She is an experienced independent content writer with a demonstrated history of working in the writing and editing industry. She is a multi-niche content chef who loves cooking new things.