phone-icon-menuSIP TRUNKS

SIP trunking provides a more flexible, scalable and lower cost alternative to traditional ISDN for both inbound and outbound business voice calls.

What is a SIP phone system?

SIP trunking (or SIP) is a public IP telephony service that’s based on session initiated protocol lines. By merging both voice and data, SIP provides a more economical option for many businesses. SIP is delivered over the same data lines used for internet and Wide Area Network (WAN) connections within your business.

By merging voice as an additional application on these data lines, the existing ISDN lines are no longer needed. SIP enables all internal calls to stay inside the company’s WAN, avoiding handoffs by the telecom provider; call charges for traversing to the PSTN. Due to this, SIP can reduce your rental and call charges dramatically.

Comparing SIP to ISDN – Why make the switch?

Infinity Group - Comparing SIP to IDSN

Our Recent SIP clients

Infinity Group - SIP Clients

The difference between SIP and Hosted Telecoms

SIP is best suited to larger SMEs and mid market businesses to ensure they can benefit from the increased flexibility and security provided by SIP trunking that a hosted telephony solution cannot offer. When you compare SIP to ISDN it often works out cheaper on a per channel basis, it’s more flexible in terms of what telephone numbers you can have and where you can have them and is quicker to install.

Another advantage of SIP is that it also provides a very robust business continuity service to ensure your business never loses calls. Calls can automatically fail over to backup analogue lines connected to your system, or to mobile devices. Unlike ISDN, DDI’s can be forwarded to different destinations at network level. They can also be configured (depending on your PBX) to failover to a secondary internet connection.

SIP is perfect for multisite businesses

For larger multisite businesses such as hotels, shops or businesses with many offices, we can usually replace the ISDN lines at multiple locations with one centralised SIP trunk – saving costs.

The 5 main benefits of SIP trunking

1: Save money by implementing SIP

SIP Trunks are significantly cheaper than ISDN and also provide savings on call costs.

2: SIP is scalable alongside your business needs

SIP Trunks can be provided with as few as 1 channel or as many channels as required. There is no need to acquire SIP Trunks in set numbers. If you required 32 ISDN 30 channels you would need to install 2 ISDN30 connections and split the channels between them and there is a minimum of 8 channels. ISDN2 provides 2 channels per connection, with a minimum of 2 channels.

3: SIP trunks are adaptable

SIP trunks can be re-provided to an alternative system or internet connection within minutes.

4: SIP enables greater flexibility

SIP trunks are easily configured and allow your system to present any phone number you require on outbound calls. Additional DDI’s can be added from almost any UK area code within minutes (Please note: Some area codes have limited availability such as 0207 and 0208)

5: Guaranteed Call Quality

Call quality is reliant on the quality of the underlying data connection. This can be assisted in correctly setting up the corporate firewall to reserve enough bandwidth for the SIP trunks.

Is it easy to switch to SIP Trunking?

Any business with a VOIP enabled private telephone network (PBX) setup can easily switch over to our SIP trunking and benefit from a cost effective and more resilient telephone service. If your business doesn’t have a VOIP enabled PBX then you might want to consider switching to Horizon our hosted telecoms solution instead.

What’s a SIP Gateway?

A SIP gateway connects to your Internet modem and relays data that it reads from your telephone system, computer software, and various devices such as microphones and webcams. A SIP gateway is often required for an office to use advanced features such as conference calls, video conferences, phone line extensions, individual voicemail boxes, and other networking features that common VoIP programs provide.

Why should you consider SIP Trunks for your business?


We look forward to discussing your SIP trunk requirements in more detail. Call or email us enquiries@infinitygroup.co.uk