3CX - PSTN, ISDN and VoIP – Part 5 - Geek Guru

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3CX – PSTN, ISDN and VoIP – Part 5


In our final blog post in this series, we look at an overall summary of the features and qualities of each type of line and how 3CX can bring them all together.


By now, you’re probably aware of the types of line available, but we feel it’s better when things are easier to compare, so we’ve put together a short summary for each of them.



  • Analogue system.
  • Simple features.
  • Standard telephone network.
  • Inexpensive line rental.
  • Each connection carries 1 line.
  • Good to have as a backup.
  • Suitable for small businesses or sole traders needing few lines.


  • Digital system.
  • More advanced features than POTS.
  • Better call quality.
  • Available in pairs of lines / connections.
  • Required for some equipment.
  • Can be used as a backup data connection.
  • For small businesses needing 8 lines or less.
  • Powered by the local exchange.

ISDN 30e

  • Up to 30 lines through a single connection
  • Same quality as 2e.
  • Additional features designed for larger organisations.
  • Upgrade or downgrade without additional installation costs.
  • Combine or split lines as necessary for data transfer.
  • Requires on-site powering.
  • Suitable for businesses requiring 8-30 lines or more.


  • Cheaper call costs especially for international calls.
  • Cheaper line rental.
  • No gateway needed.
  • Reliability and uptime match or exceed standard telephone networks.
  • Many advanced features.


3CX IP-PBX systems can work with any of the above, or all of them together if you prefer. They can provide your organisation with a multitude of advanced features at far less cost than a standard PBX system, with enhanced flexibility.

It’s possible to have a part-VoIP, part-ISDN network running seamlessly with a standard POTS line as a backup, if necessary – through the use of gateways to connect the external POTS and ISDN systems to the IP-PBX. Even though a gateway is required, installation and hardware costs of these systems are still significantly less than you’d expect to pay for standard PBX with similar features. They are also easily upgradable to meet your needs, adding an additional internal line can be as easy as plugging in an additional computer and headset and telling the 3CX control panel it’s there.

No matter what type of line you choose, we’re sure you’ll enjoy the enhanced flexibility of a 3CX IP-PBX system along with it.

At Geek Guru, we provide, install and support 3CX systems, so if you’re considering making the switch to VoIP or just want to upgrade your existing PBX system to a more versatile 3CX system, get in touch with us.


If you’d like to discuss 3CX Systems, VoIP, ISDN or anything else IT or tech-related with us, give us a call and we’ll be happy to help you in any way we can!

Call us on 0845 234 0580 or email us at info@geek-guru.co.uk

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Posted on by Emily
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