0343 507 1111
My Account

Get a no-obligation quote on our award-winning telephone systems. You could save up to 70% on your communications bill by switching to us!

SIP vs ISDN vs Analogue

SIP vs ISDN vs Analogue

What is SIP?

‘Session Initiation Protocol’ is a protocol of VoIP which allows users to make voice and video calls. Essentially, it allows the internet to be used to carry calls, just like a phone line.

Advantages of SIP

  • SIP calls are the cheapest to make and are often free to make when made to other SIP phones depending on your provider
  • International calls are significantly cheaper to make than with ISDN or Analogue phones
  • More affordable scalability – cheapest to add more lines to the phone system
  • Can integrate mobile devices with a SIP phone system
  • SIP phone systems give you features, such as video conferencing or visual voicemails that aren’t available on ISDN or Analogue phone systems
  • More future-proof than ISDN or Analogue phones

Disadvantages of SIP

  • Call quality is reliant on your internet speed and quality
  • If your Internet goes down so does your SIP phone system, unless on a dedicated line

What is ISDN?

‘Integrated Services Digital Network’ is a technology that allows the transmission of digital data through PSTN lines (traditional phone lines).

Advantages of ISDN

  • ISDN can provide higher data speeds than Analogue
  • Calls are always crystal clear and there is no reliance on having good internet

Disadvantages of ISDN

  • Is more expensive to install additional lines compared to SIP
  • More expensive to make calls using ISDN than with SIP
  • International calls are significantly more expensive to make than using SIP
  • Their use in the UK is dying as BT has announced that by 2025 they will shut down their ISDN lines

What is Analogue?

An Analogue phone system works through copper wires that are connected from your local telephone exchange to your office. Once your analogue line is installed, your local telephone exchange will allow you to be connected to the Public Switched Telephone Network (PSTN) where your inbound and outbound calls will be travel through.

Advantages of Analogue

  • Analogue phones can still be used during a power outage
  • They can also support Fax machines

Disadvantages of Analogue

  • More expensive to make calls using Analogue than with SIP
  • International Calls are very expensive
  • Is more expensive to install additional lines compared to SIP
  • Least feature packed out of ISDN and SIP
  • BT are also looking to kill off their PSTN lines as well by 2025


Summary Table – SIP vs ISDN vs Analogue

SIP ISDN Analogue
Benefits Drawbacks Benefits Drawbacks Benefits Drawbacks
Cheapest calls Reliant on good internet Higher data speeds than Analogue More expensive calls than SIP Can be used during power outage More expensive calls than SIP
Calls can be free to people using SIP phones Goes down with internet Crystal clear voices More expensive international calls Can support fax machines More expensive international calls
Most affordable scalability More expensive to add users than SIP More expensive to add users than SIP
More features BT to kill their ISDN lines by 2025 Least feature-packed
Phone Integration BT to kill their PSTN lines by 2025

Hybrid Phone Systems

A Hybrid Phone System allows you to use more than just one type of technology which is perfect if you want to take advantage of SIP but still want to use lines that you may already have in place. Check out our blog on hybrid phone systems if you want to find out more.

If you are interested in either phone system for your business or are still unsure of what system to go for, please emails us at info@lilycomms.co.uk or call us on 0343 507 1111 so we can help.

#s4s #bizfit

What is #bizfit?

We’re currently running the ‘Trade-In’ offer as part of our #bizfit campaign. Get up to £5000 off any new phone system when you trade in your old one. Additionally, get up to 1 million minutes for free when the system you purchase utilises SIP channels Click here for more information