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...
06/09/2026
June 9 2026, 23:00 (PDT) Dolby and MagentaTV Bring Fans Closer to the FIFA Worl...
21/08/2026
Hardware-style timing shifts for software instruments
Following on from the release of Omniclock, Rapid Flow have launched a new sequencer plug-in that can ...
21/08/2026
Highly anticipated synthesizer ships in October 2026
Iceland-based Love Synthesizers have announced that their highly anticipated synthesizer is now availab...
21/08/2026
Masterpiece PBS The Forsytes has expanded its cast as its begins production in ...
21/08/2026
The BBC has unveiled first-look pictures from The Witch Farm, a new ghost story and mystery set in the Welsh countryside, coming soon to BBC iPlayer and BBC One...
21/08/2026
The BBC and BritBox have revealed the first look of Edward Bluemel as Hercule Poirot in the forthcoming six-part series Hercule from Mammoth Screen and Agatha C...
21/08/2026
eds3_5_jq(document).ready(function($) { $(#eds_sliderM519).chameleonSlider_2_1({ content_source:......
21/08/2026
** MEDIA ALERT **
VIZ Media Takes Over Anime NYC with BLEACH, BLACK TORCH, M...
21/08/2026
Tell us a little bit about your job I'm a Marketing Manager and work across a mix of clients and projects. No two days are ever quite the same, which defini...
21/08/2026
Beat The Lotto dives into the plot behind the 1980s National Lottery scandal
24 August 2026 at 9:35pm on RT One and RT Player
Beat The Lotto is the story o...
21/08/2026
The countdown to the most wonderful night of the year has officially begun!
Host Patrick Kielty is gearing up for another unforgettable Late Late Toy Show nig...
21/08/2026
Meet puppet duo Bellie and Whizz, who are about to explore all the big feelings ...
20/08/2026
Set up your own private remote collaboration infrastructure
SoundBridge have recently put together a tutorial video that provides users with a step-by-step ...
20/08/2026
New V-Control Pro features restore basic functionality
Neyrinck's V-Control software has long been keeping older Avid control surfaces compatible with n...
20/08/2026
TV, BritBox and Mammoth Screen have announced that filming is now underway on th...
20/08/2026
Thursday 20 August 2026
Nina Sosanya, Rizzle Kicks, Roman Kemp and Paul Whiteho...
20/08/2026
Wuppertal August 20, 2026
Transformation Church Elevates Production Communicat...
20/08/2026
The music between the notes Coming together In the middle of 2026, as conversations around artificial intelligence continue to raise questions about how musi...
20/08/2026
Arvato Systems Brings Together Digital Transformation Leaders in the Manufacturi...
19/08/2026
Studio owners invited to have their say on rates cuts
The Music Producers Guild (MPG) are inviting UK-based studios to take part in an in-depth survey that ...
19/08/2026
Vintage-inspired desktop interface revealed
Harrison's latest hardware offering sees them head into the world of audio interfaces, delivering a 10-in/12...
19/08/2026
Granular effect remains locked to scale and tempo
Described as your dream granular effect , Minimal Audio's latest creation is capable of turning any s...
19/08/2026
First polyphonic SWAM instrument incoming
Audio Modeling's latest physical-modelling orchestral instrument is just around the corner, and is now availab...
19/08/2026
There's an early Christmas gift for Bookish fans, as UKTV confirms the re-commission of the hit U&alibi drama, created by and starring Mark Gatiss. Viewers ...
19/08/2026
Wednesday 19 August 2026
Sky gives sports fans the chance to watch multiple liv...
19/08/2026
On Saturday September 5 Katie Taylor will step into the ring for the fight of her life against Flora Pili in front of 80,000 fans in Croke Park. A legendary fig...
18/08/2026
Company launch with stereo-imaging tool
Panoramic is the debut release from Panorama Labs, a new company formed by mastering engineer Nicholas Di Lorenzo. C...
18/08/2026
Control software now available for older interfaces
Focusrite have just announced the launch of an update that extends Control 2 software support for their ...
18/08/2026
Tuesday 18 August 2026
Sky Sports and The Fast and the Curious announce new partnership
Sky Sports and The Fast and the Curious have announced a new long-term...
18/08/2026
Wuppertal August 18, 2026
Riedel Brings Professional Live Production Into the Classrooms of ECURiedel Communications today announced that Edith Cowan Universi...
18/08/2026
Apple today announced changes to its business terms for apps in the European Uni...
18/08/2026
THE HEALY RAES: BLOOD, SWEAT & TEARS AIRS WEDNESDAY AUGUST 19 ON RT ONE AT 9:35PM
A new documentary The Healy-Raes: Blood, Sweat & Tears airs on RT One and ...
18/08/2026
Stunning Irish performances at European Athletics and Swimming Championships rea...
18/08/2026
The two-part series begins Sunday 23 August at 6.30pm on RT One and RT Player
...
17/08/2026
New MIDI processor & macro controller revealed
SHIK have announced that they have opened pre-orders for the S32, a standalone MIDI processor and macro contr...
17/08/2026
Cover extended on innovative motorised pot system
Melbourne Instruments have just revealed that the innovative motorised pot system used in their synths and...
17/08/2026
Latest firmware version now available
1010music have just released a free firmware update that brings some nice new features to their renowned Bluebox digit...
17/08/2026
Rohde & Schwarz showcases integrated defense and test solutions at DALO Industry...
17/08/2026
Calrec's ImPulseV Virtualised Audio Mixing Engine joins NEP Platform, the industry's largest ecosystem of trusted production software, bringing scalable...
17/08/2026
Visitors to IBC 2026 will see how FilmLight is reshaping the modern post pipelin...
17/08/2026
Visitors to Stand 1.C41 can explore innovations in areas such as addressable advertising, hybrid distribution, managed services and operational simplification.
...
16/08/2026
Virtual drummer joins line-up
The latest release from Gospel Musicians adds a virtual drummer to the company's line-up, combining a pair of meticulously...
15/08/2026
In-ear monitoring line-up gains new universal models
In-ear monitoring experts JH Audio have just announced a significant expansion of their Universal-Fit r...
14/08/2026
Latest instalment delivers disco-inspired grooves
The latest addition to UJAM's virtual drum line-up has been designed with contemporary pop, disco, dan...
14/08/2026
Elite range gains giant 24-inch powered sub
The latest expansion of Yorkville's Elite range introduces what the company say is the world's first act...
14/08/2026
Friday 14 August 2026
Breaking news! Sky releases trailer for The Paper, return...
14/08/2026
It's been one year since our client, Cotswolds Designer Outlet, opened its doors and we've loved seeing the scheme come to life. Together, we've hel...
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.
