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...
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 their Scar...
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...
13/08/2026
Company preview bio-interactive' synthesizer
VAEMI have announced the upcoming launch of a new standalone bio-interactive' generative synthesizer....
13/08/2026
Plug-in host gains new Slot Scenes feature
Ravine DSP have recently updated their innovative plug-in host, kitting it out with a new feature that brings yet...
13/08/2026
New U and U&W Documentary Features Kathleen Richards, One of the Last Surviving Witnesses to Fred and Rose West
Kathleen is Reunited with Childhood Friend and ...
13/08/2026
Thursday 13 August 2026
Official trailer released for the return of Tea with Ju...
13/08/2026
Dalet, a leading technology and service provider for media-rich organizations, t...
13/08/2026
Wenvoe serves over 1 million people across South Wales
13 August 2026, Winchester, UK - Vale of Glamorgan MP, Kanishka Narayan, has praised the engineering exp...
13/08/2026
RT 's Miriam O'Callaghan welcomed a range of specially invited guests to the National Concert Hall last week for a unique event to mark a new season wit...
13/08/2026
August 13 2026, 06:00 (PDT) Seattle Seahawks Become First Team to Bring Dolby O...
12/08/2026
Enhanced DAW & plug-in control for the UC1, UF8 and UF1
The software that powers SSL's range of control surfaces has just received a major update that d...
12/08/2026
In-line preamp features one-knob EQ
In addition to their range of in-line preamps, Triton Audio recently managed to squeeze a compressor into an enclosure t...
12/08/2026
Captures system audio with or without a DAW
Depending on your setup, capturing system audio in a DAW can be a tedious process, so much so that Arvital Audio...
12/08/2026
Comscore Reports Second Quarter 2026 ResultsRESTON, Va., August 12, 2026 Comscore, Inc. (Nasdaq: SCOR), a trusted partner for planning, transacting and evalu...
12/08/2026
NEW BOOKSHOP OPENING IN LONDON THAT OFFERS NEW IDENTITIES, NOT BOOKS, WITH FREE ...
12/08/2026
Brand-new trailer unveiled as Sky announces SNL UK ticket ballot will open on 14...
12/08/2026
Wednesday 12 August 2026
Sky Sports agrees deal to show Laver Cup from London's O2
Sky Sports has agreed a deal with Trident8 to show all three days of th...
12/08/2026
Wednesday 12 August 2026
Pre-order the new Google Pixel 11 range from today and...
11/08/2026
Free library captures pro classical string section
There's no shortage of freebies in The Crow Hill Company's line-up, with their Vaults series offe...
11/08/2026
Percussion instrument introduces all-new engine
Emergence Audio have just introduced an instrument that brings together a vast collection of percussive anal...
11/08/2026
Introduces new all-in-one Spatial Panner tool
Boris FX have recently announced the latest major update for their mastering and broadcast-focused DAW softwar...
11/08/2026
Rohde & Schwarz installs millimeter wave security scanners at Airports of Thaila...
11/08/2026
Comscore Announces ROI Strategy to Transform the Business Centers around three core objectives: Realign the Business, Optimize the Organization and Invest in Fu...
11/08/2026
Whether gamers are looking for high-octane action or a laid-back afternoon, Appl...
11/08/2026
Hosts D ith S and Kathryn Thomas rose to the occasion on Tuesday (August 11)...
11/08/2026
A Day in May airs Wednesday 12 August at 9.35pm RT One and RT Player
A Day in May revisits the people and stories behind Ireland's historic marriage equa...
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.
