SIP Trunks – This is not SIP trunks for dummies, it’s SIP for anyone

3rd August 2020

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Let’s just start by unwinding the actual acronyms and give them some simple terminology before we go through the benefits of Session Initiation Protocol, yes that’s it… Session Initiated Protocol – SIP. This is not SIP trunks for dummies, it’s SIP for anyone that’s not a tech in the communication provider sector.

SIP Trunks - Session Initiation Protocol.

SIP are also referred to as SIP trunks, although the term ‘trunks’ doesn’t actually apply to SIP-based communications because there are no physical wires or connections. This term is widely accepted within the industry, however.

SIP – stands for Session Initiation Protocol and is an Internet Protocol standard established by the Internet Engineering Task Force.

ISDN – Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network.

VoIP –Voice over Internet Protocol, also known as IP telephony, is the transmission of voice content over the internet.

PBX – Private Branch Exchange, which is a private telephone network used within a company or organisation.

ITSP – Internet Telephony Service Provider, offers digital telecommunications services based on Voice over Internet Protocol.

PSTN – Public Switched Telephone Network is the aggregate of the world’s circuit-switched telephone networks, which are operated by national, regional, or local telecoms operators, providing infrastructure and services for public telecommunication.

SIP trunks are a modern alternative to ISDN lines that most organisations use to make phone calls. The most common way to connect to the public switched telephone network (PSTN) was through a private branch exchange (PBX) allowing a company to allocate phone lines and numbers among hundreds or thousands of employees.

SIP lets you do the same thing, but it’s cheaper and more efficient. SIP trunks route voice calls over the Internet, just like how images, sound and documents travel over the Internet. It means you don’t have to maintain two separate networks, one for data and another one for phone calls.

Now you know why many businesses find it too intimidating to even consider changing the system they have, especially when someone trying to explain all this is talking another language.


How Can SIP Trunks Help Your Business?

When you switch to SIP trunking, phone calls travel over the Internet similar to other forms of media. You eliminate extra maintenance costs by combining all your communication needs into one service rather than two. You can send video, instant messages and voice calls through the same system instead of using different software for each, bringing together different services like voicemail, IVR etc in one neat package. You can even integrate SIP trunks with other enterprise software like CRM and ERP systems, which can greatly improve productivity.

Upgrading to SIP trunks can be one of the smartest decisions you can make for your business today. Just make sure to do your research before upgrading and you’ll start seeing benefits almost immediately!


Inbound vs Outbound SIP Trunks

There are many ways to classify phone calls, some are voice only while others include video. You can also group calls according to how many people are participating, so you can have one-to-one calls or conference calls with multiple speakers.

You can also classify calls according to the direction they travel. Calls that employees make to external entities – customers, partners, suppliers etc. – are called outbound calls whilst inbound calls go in the opposite direction. When customers or anyone else from outside the business contact someone inside, it is an inbound call.

The distinction between inbound and outbound calling may seem trivial, but it’s actually important because you can separate the two. For instance, a company may decide to use SIP trunks for outbound calls only. They can continue using the existing PRI lines for inbound calls.

Why would you do that? A business may want to ease into the transition to VoIP gradually. They may have existing equipment that they don’t want to throw out immediately. Some businesses like to test new equipment before committing wholeheartedly to it. Whatever the reason, you can use SIP trunks in a single direction only.


The Differences between Inbound vs Outbound Calling

There are a plethora of features that SIP trunking offers, in conjunction with an IP PBX. Some features affect inbound calls only, while others impact outbound calls.

The most common features that businesses use for inbound calling are:

Voicemail – You have multiple options here. You can have visual voicemail delivered directly to employee inboxes. You can enable automatic transcription and recording.

Call routing – Any modern business has complex routing needs. You may have some employees working from home, from a client site or travelling. But no one should miss incoming calls. You can set up routing rules which dictate where calls should go, based on time or other variables.

Toll-free & DID numbers etc – Toll-free numbers allow customers to contact you without incurring long-distance charges. DID numbers allow you to assign direct numbers to certain employees, without maintaining separate physical lines.

On the other hand, examples of outbound calling features are:

Integration with CRM software – This allows staff to call customers from within an application. There is no need to switch apps just for a call.

Caller ID – This is a crucial feature for any business. Any call going from your company has to show the correct number on the caller ID. With VoIP, you can show the correct number even if you are using a different device or calling from a different location. The customer never has to know that you’re not at your desk.

Call data records – Most businesses maintain detailed call data records. You need the data to analyse call volume, traffic, and spot issues before they blow up.

Should You Use Both?

Although you can use just one, most companies prefer to go all-in with SIP trunking. That’s because the upgrade almost always saves money. While the exact amount might differ from one company to the next, practically no one will spend more on VoIP than older landlines.

Upgrading all at once also saves you time – you don’t have to implement the project in phases. You don’t have to reconcile two types of equipment at the same time. There are very few instances where enterprises go back to landlines after using VoIP. So, it makes sense to deploy the entire system at once.


As always, evaluate your requirements and select a system that suits your needs.

SIP is a cost-effective replacement for traditional voice services, connecting your PBX seamlessly to the PSTN. You can choose to have a complete SIP solution – or to combine it with IDSN to give you a truly resilient communications package.

SIP provides a highly flexible alternative to traditional voice services and is compatible with all the leading IP PBX brands in the UK market. Our service can support connections ranging from a single channel for businesses with small PBXs to solutions with no limit on the number of channels for larger enterprises and contact centres.

Still don’t understand how it all works together?

Don’t be intimidated, the team with the knowledge to bust the jargon for you is at Elite Group. The knowledge and information they can offer will allow you to deploy a system that fits your business perfectly, saving you time and money.

Elite Group are a highly trusted and leading UK SIP trunk provider so call or email today!, don’t be embarrassed if you have no idea what you’re talking about – it could be costing your business if you don’t.