Circuit switched networks physically connect two endpoints using a communication channel through the network. This utilises a fixed bandwidth for the session whilst the two endpoints remain connected. Packet switched networks offer the ability to split the communication channel into small packets to be sent across the network using multiple routes offering redundancy and increased performance. This utilises dynamic bandwidth management which can be optimised for each connected party and allows for many more services and connections to be active at the same time using the same bandwidth.
In the cellular network GSM (2G) and UMTS (3G) use circuit switching for voice, circuit switched dialup (CSD) and short messaging service (SMS) traffic and use packet switching for GPRS data traffic. In LTE (4G) the entire network uses packet switching and has no capability for circuit switched network support. As a result, the voice and SMS services must be moved over to a packet switched network when using the LTE (4G) network. In addition to this, CSD is no longer supported and GPRS data must be used instead.
Please see Circuit Switched Dialup (CSD) Migration to LTE Application Note' here.
Voice Overview Many applications in use today utilise voice as part of the service offering. This may be to connect two parties together to communicate such as in an elevator emergency failure system, to implement an automated payment service using a dial keypad or report a fault with a system using normal spoken language. Whatever the reason for using the voice service in a cellular system, there are some differences with the LTE network which are described in more detail below.
On legacy devices supporting GSM (2G) and UMTS (3G) services, the voice and SMS components of the system use circuit switching as the transmission channel. For GSM the whole system was built on an analogue infrastructure and digital data was added to the system later with the advance of GPRS packet data. The UMTS system is based on the GSM standard and therefore also supports both digital and analogue components. The UMTS framework allows much higher data rates over GSM but is still based on a similar infrastructure.
LTE on the other hand is entirely digital and has no analogue components at all. Therefore, new methods are used to take advantage of the new features offered by the LTE network as analogue voice calling is no longer possible and the packet switched network must be adopted.
VoLTE (Voice over LTE) Overview The LTE network supports voice and many other additional services in the same way as GSM and UMTS, however, as there is no analogue component the voice must be encoded and sent digitally across the network using packets. The 3GPP body have specified the voice service on LTE which is highly optimised and takes advantage of the additional bandwidth and low latency of the LTE network. This service is called Voice over LTE (VoLTE) and uses the digital packet switched network in a much more efficient way than traditional services. This means that VoLTE can support up to 3 times more voice capacity than previous UMTS networks and up to 6 times more capacity than older GSM networks.
The VoLTE service is provided on LTE over the IP Multimedia System (IMS) network service which is a standardized framework for delivering multimedia services over TCP/IP. It has been developed to allow all content rich media from wireless and wireline applications and allows for advanced services to be provided over the existing infrastructure without the need for individual control functions for each service.
The network provider must support IMS to be able to offer VoLTE as a service to its customers. The IMS framework must be integrated within the network's core architecture and is fundamental to the operation of the network.
Network Usage with Circuit Switch Fall Back (CSFB) With existing GSM (2G) and UMTS (3G) networks, the core functions are built into the application and can be supported with any hardware platform that supports voice and any SIM card that supports voice. This allows for a very simple implementation and calls can be established without any special configuration to the end equipment.
With newer modems that support LTE (4G) in addition to GSM (2G) and UMTS (3G) the firmware in the modem performs a subtle trick to continue having seamless voice support. When connected to the network for transmitting digital packet data, the unit connects to and uses the LTE network. When attempting to dial a voice number the unit automatically switches to UMTS (3G) or GSM (2G) to establish the call. Once the call is finished it reverts to the LTE network. This technology is called circuit switch fall back and is a short-term solution to allow all network providers to offer voice services on the LTE network whilst they implement their own full IMS solution.
This process is fine whilst there are UMTS (3G) and GSM (2G) networks available to use but the analogue networks are being gradually sunset to be replaced entirely with the LTE network.
With the LTE (4G) network it is necessary to configure the device to allow calls to be made using the LTE only network over the IMS service.
SMS Overview The short messaging service (SMS) can be used to send and receive small text messages which can be used in a variety of ways for applications that use the cellular network. The messaging service can be used to configure settings in remote equipment as well as reporting on the current configuration. In addition, the messaging service can inform users directly of a triggered alarm state or indicate when a certain criterion has been met. As with voice, the existing GSM (2G) and UMTS (3G) core functions are built into the system and can be supported with any hardware platform that supports the SMS messaging service and any SIM card that has SMS functio
Europe Stories
05/01/2027
Worlds first 802.15.4ab-UWB chip verified by Calterah and Rohde & Schwarz to be ...
07/10/2026
Dalet, a leading technology and service provider for media-rich organizations, today announced the latest Long-Term Supported (LTS) release of Dalet Flex. Build...
09/09/2026
New parts aimed at hip-hop and pop productions
The latest update to Celemony's innovative virtual session musician expands the collection of built-in in...
09/09/2026
Save up to 40% until 21 September 2026
Sonarworks are currently running their Autumn Sale, with discounts of up to 40% currently available across their rang...
09/09/2026
Upcoming title officially launches in September 2026
Bjooks' celebrations for this year's 909 Day will be welcome news amongst drum machine lovers, ...
09/09/2026
Wednesday 9 September 2026
Tom Daley adds final stitch to giant Baa-Ewe' t...
09/09/2026
Red Seat Ventures Integrates Barometer into Speakeasy to Maximize Podcast Revenu...
09/09/2026
Baselight-powered color comes natively to Media Composer, connecting creative de...
09/09/2026
RT brings three packed days of live radio, entertainment, news, weather and fun
Join RT Radio 1: Morning Ireland, Oliver Callan, Today with David McCullagh,...
08/09/2026
Built for rap producers, by rap producers
Sauceware Audio, the independent plug-in company founded by Grammy-nominated producer Jacob (Travis Scott, 21 Sava...
08/09/2026
Classic Sound Techniques design revived
Warm Audio's latest release delivers a meticulous recreation of the preamp circuitry employed by the Sound Techn...
08/09/2026
Latest soft synth inspired by the Memorymoog
XILS Lab have just launched a software instrument that draws its inspiration from Moog's iconic Memorymoog,...
08/09/2026
September 08, 2026 NORTHRIDGE, Calif. - Soundcraft today announced the launch of its Signature Plus Series Analog Connected Mixing Consoles. As the next genera...
08/09/2026
Tuesday 8 September 2026
Sky Go gets a major upgrade for Sky Glass and Sky Stream customers
Today, Sky launches a new version of the Sky Go app for Sky Glass ...
08/09/2026
Documentary thriller simulating a Russian attack on UK soil will culminate in a live final episode reuniting the playersTuesday 8 September 2026
Trailer releas...
08/09/2026
Tuesday 8 September 2026
Jamie Demetriou and Amelia Dimoldenberg to host next t...
08/09/2026
Wuppertal September 8, 2026
Riedel Introduces New OnAir Headset PlatformRiedel Communications today announced the launch of its new OnAir headset platform, a...
08/09/2026
BERLIN, September 8, 2026 - J nger Audio will introduce a major expansion of its flexAI audio processing platform at IBC 2026. The flexAI system adds autonomous...
08/09/2026
New Vendor-Agnostic Broadband Intelligence Fabric Reduces Operational Complexity and Improves Service Quality for Broadband Service Providers SAN JOSE, Calif. -...
08/09/2026
Arvato Systems Brings TI Expertise to the Stage
Panels, workshops, and real-world examples at the TI-SUMMIT 2026
Arvato Systems, a partner of the TI-SUMMIT 2...
08/09/2026
On October 1, Apple Arcade is rolling out a lineup of fun new games for players ...
07/09/2026
Two new full-range, flat-response cabinets introduced
HeadRush have recently introduced a pair of new full-range, flat-response cabinets designed for player...
07/09/2026
Answering questions about AI in game audio
GameSoundCon, the largest professional conference for video game music and sound design, have announced that they...
07/09/2026
New directional headset mic on show at IBC
Just ahead of this week's IBC show, DPA have announced the launch of a new directional headset that's bee...
07/09/2026
We are not building systems to replace human decision-making; we are building systems that execute our decisions at machine speed. The media companies that win ...
07/09/2026
Monday 7 September 2026
Freddie Meredith joins cast of SNL UK ahead of start of Season 2
Freddie Meredith Images
ZIP (3MB)
Saturday Night Live UK announces ...
07/09/2026
Monday 7 September 2026
Sky and NFTS team up to launch new routes into screen careers
Sky has today announced a new apprenticeship programme, with application...
07/09/2026
Monday 7 September 2026
Sky Sports announces most comprehensive NFL coverage to...
07/09/2026
Dolby, MainConcept, Techex and J nger Audio will showcase the industry's first demonstration of Serial Audio Definition Model (S-ADM) in a cloud-based produ...
07/09/2026
dB Broadcast will showcase APIS Hive, its software platform for designing, deploying and managing modern broadcast infrastructures, at IBC 2026.
Developed from...
07/09/2026
552,000 streams on RT Player
The historic fight, which saw Katie Taylor become...
06/09/2026
Recreates Rolands TB-303 & MC-202
BS-203 MacroAcidizer is the first virtual instrument from Born Second, and it offers a recreation of two Roland classics -...
06/09/2026
June 9 2026, 23:00 (PDT) Dolby and MagentaTV Bring Fans Closer to the FIFA Worl...
05/09/2026
MK2 & Bass system control app improved
HEDD Audio have just launched a new and improved version of the control software that pairs with their MK2 and Bass m...
04/09/2026
Media organisations interested in the Media Innovation Europe 3.0 Business Innovation Synergizer (BIS) can now consult a new FAQ document providing additional a...
04/09/2026
Powerful new soft synth announced
Traveler is the first software instrument to be released by KeySolutions Sounds, and it's an ambitious one! Said to co...
04/09/2026
Free virtual instrument range expanded
The latest expansion of e-instruments' free Fragments series introduces a packed-down version of the company'...
04/09/2026
Company recognised for second time
Two years after winning an Engineering, Science & Technology Emmy Award for dxRevive Pro, Accentize have been recognised ...
04/09/2026
Bilbao - 3rd September 2026 -AgileTV, a leading provider of end-to-end TV and vi...
04/09/2026
RT ANNOUNCE NEW DRAMA THE MURDER OF MR. MOONLIGHT
BASED ON THE DISAPPEARANCE...
03/09/2026
Yospace will be at IBC from 11th - 14th September (booth 5.C78). For more inform...
03/09/2026
Create musical synth bass sounds from scratch
Anthony Marinelli Music have recently announced the launch of Bass DNA, a new online course that teaches music...
03/09/2026
Most powerful Tonex hardware to date
IK Multimedia's latest release introduces their most advanced Tonex hardware unit to date, combining their AI Machi...
03/09/2026
Upmix & downmix software upgraded
Penteo Audio Plugins have announced that the latest version of their powerful upmix and downmix software is now available....
03/09/2026
With the start of the new apprenticeship year, young talent has once again begun their professional careers at SGL Carbon's sites in Germany. Recently, the ...
03/09/2026
With the industry increasingly embracing hybrid, software-defined production models, Calrec will preview a series of Argo and ImPulseV software enhancements at ...
03/09/2026
Luxembourg, 03 September 2026 - SES, a space solutions company, extends its collaboration with the Peruvian Navy (Marina de Guerra del Per ) to deliver sovereig...
03/09/2026
Thursday 3 September 2026
Jeff Goldblum announced as host of Saturday Night Liv...
03/09/2026
Wuppertal September 3, 2026
Gonshiro Strengthens Collaboration With Riedel, AR...
Circuit switched networks physically connect two endpoints using a communication channel through the network. This utilises a fixed bandwidth for the session whilst the two endpoints remain connected. Packet switched networks offer the ability to split the communication channel into small packets to be sent across the network using multiple routes offering redundancy and increased performance. This utilises dynamic bandwidth management which can be optimised for each connected party and allows for many more services and connections to be active at the same time using the same bandwidth.
