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Hosted Telephony

The future of connectivity

Why choose hosted telephony with Gamma Horizon?

  • Your phone system hosted in enterprise data centres

  • Flexible system for a mobile business

  • Deliver voice to any user with an internet connection

  • Platform to build a mobile workforce (fixed-mobile convergence)

  • Get new features immediately

  • Accessible over an internet connection

  • Packaged to meet the business required

  • Fully managed and deployed by TSG

  • Industry-leading SystemCare support

What are my options?

Voice services have evolved since ISDN’s birth some 30 years ago. With ISDN’s end of life in 2025, now is a great time to look at your business’ voice strategy and how you deliver services to not only your customers but also your employees.


Traditional, on-premise phone systems (PBXs) are ultimately voice servers hosted in your office environment, connecting to the public telephone (PSTN) network via some sort of access circuit. Older systems could be on ISDN (see end of life) with newer on-premise systems utilising SIP trunks, delivering the telephone line over a data connection.

These systems play a role depending on your business requirements and TSG is well placed to assess your requirements and business plans and advise whether on-premise, hosted telephony or fixed-mobile convergence is the best route for you.


Next-generation VoIP (Voice over IP) systems are being provided to businesses in a hosted environment, leveraging the move to cloud-based technologies.

The PBX is typically hosted within a cloud datacentre and in TSG’s chosen platform, Gamma Horizon, with updates being made available to users on a regular basis without having to plan engineering or downtime for the business.

With the PBX hosted within the datacentre, access to the system is via either a dedicated or converged data connection (ADSL, FTTC or Ethernet) with remote users being able to use their broadband service to access the system. Users have the choice of either industry-leading hardware (Polycom VVX IP phones) or softphones.

TSG’s hosted platform has been designed to be fully managed and supported via the TSG SystemCare teams, whilst providing a cost-effective route to get enterprise-grade telephony functionality within your business.

Fixed-mobile convergence (FMC)

Voice services and how we consume them as businesses is rapidly changing, with many organisations offering flexible working, meaning many employees work away from traditional offices. This lends itself well to hosted telephony, but the next generation of hosted telephony is here with fixed-mobile convergence.

Utilising the users’ mobile phone, users are part of the corporate phone system. A single number reach for both customers and colleagues provides one voicemail platform and delivers features from a phone system to the native iOS and Android platforms, all via the mobile phone network.

This allows mobile staff to have the same features office-based staff have without the overhead of connectivity and additional hardware.

FMC eliminates the quandary that employees and customers have when wanting to reach out to your staff of which number is best to call them on. This streamlines the communication channels into the business.

All FMC users are also able to act as part of a hunt group, call centre environment and have all calls recorded via the platform. Add the reporting features to this, and businesses are able to gain a view of the troublesome mobile estate whilst managing them from the same interface as the fixed line users.

What are my next steps?

As you can see from earlier, the telephony world is evolving and new features are being made available every month via the hosted and fixed-mobile convergence platforms.

TSG has a team of experts who live and breath telephony and are happy to assist in any way that we can. Typically, upon engagement, the team will discuss:

  • Understanding your current setup

  • What works for your business

  • What doesn’t work for your business

  • Network connectivity and requirements

  • Future plans for the business (digital transformation, changes in structure, growth, etc)

  • What you would like a voice platform to do for your business

From this, we will be able to build and advise on a voice strategy, not only for today, but looking towards the future with you, working in partnership.

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