Applicable Products Part number Description
SL500-LTE1 (EU) SL500-LTE1 (EU) Low Power LTE Cat 1 Serial Gateway
SL500-LTEM (GL) SL500-LTEM (GL) Low Power LTE Cat M / NB IoT Serial Gateway
CSD Overview Many aging applications in use today utilise the circuit switched dialing (CSD) service available on older style modems and communication devices. The CSD service allows a device to connect to a remote location using a dial up modem and establish a direct low latency connection to the host.
The benefit of using CSD connections is the simplicity with which the connection can be established and many applications still use dial up services on their equipment to establish an internet connection to their devices. However, this is slowly changing, and much effort is being put in to modernizing the internet connectivity available in remote locations.
On a more modern device supporting 2.5G and EDGE IP data services, the CSD service is being replaced with a PPP dial up adapter on a host PC using a special call id *99***1#' which establishes an IP packet data connection over a dial up adapter.
The CSD service also allows for connections to be made to the device from multiple locations, where the dialling party simply needs to know the devices' data phone number to be able to dial the units directly and establish a connection to the connected equipment.
CSD Connection Speed The downside of CSD data connection services is that the maximum bandwidth available on a 2G connection is limited to 57.6 kbps and in most applications is limited to 9.6 kbps. In today's fast connected world these are very slow speeds and it would take a long time to download even basic information presented with modern systems. The other issue is the cost of downloading large amounts of data. CSD is charged for by the minute and the time taken to download a 1M file is shown in the following table.
Modem Speed Time Taken (min:sec)
9.6 kbps 15:16
14.4 kbps 10:11
28.8 kbps 5:05
33.6 kbps 4:21
56.7 kbps 2:37
So even at the fastest possible speed it would still take nearly 3 minutes to download the file and as this is charged for by the minute this would cost in the region of £0.15-£0.60 depending on the cost of your call charges.
CSD Supported Cellular Technology CSD data services are available on 2G/GSM and 3G/UMTS cellular data carriers. CSD is not supported at all on 4G/LTE due to the digital IP packet based technology used. As a result, any LTE modem which claims support for CSD will automatically fallback to 2G or 3G when establishing a data call. The same is true for analogue voice calls which are also not supported at all on 4G networks. To perform a voice call exclusively on the 4G network it is necessary to use the VoLTE service offered by the IP Multimedia Core Network Subsystem (IMS).
Not all modern modems support IMS and therefore they only support CSD and Voice calls over the 2G and 3G core networks. This means that when the 2G and 3G networks are finally sunset then these modems will stop working for data calls completely and voice calls unless VoLTE is used.
The latest range of Siretta LTE Category 1 and LTE Category 4 modems support IMS over LTE in addition to CSD and Voice over 2G/GSM and 3G/UMTS network technologies. As a result you can be sure when using a Siretta modem you will be able to support all technologies straight out of the box and the services available to you to use will be dictated entirely by your SIM card provider. The details of the SIM services available on 2G (GSM) / 3G (UMTS) / 4G (LTE) and LTE Cat M and LTE Cat NB IoT are described in the following section.
ZETA Model LTE Category
LTE Region UMTS Region GSM Region IMS Support
GPRS Support
CSD Support
SMS Support
ZETA-NLP-LTEM (GL) M/NB GL
GL
Yes
Yes
No
Yes
ZETA-NLP-LTE1 (EU) 1 EU
EU
EU
Yes
Yes
Yes
Yes
ZETA-NSP-LTE1 (EU) 1
EU
EU
EU
Yes
Yes
Yes
Yes
ZETA-NEP-LTEM (GL) M/NB
GL
GL
Yes
Yes
No
Yes
ZETA-NEP-LTE4 (EU)
4
EU
EU
EU
Yes
Yes
Yes
Yes
ZETA-GEP-LTE4 (EU)
4
EU
EU
EU
Yes
Yes
Yes
Yes
ZETA-N-LTE (EU)
4
EU
EU
EU
No
Yes
Yes
Yes
(GL) = Global Region | (EU) = European Region
SIM Configuration To support CSD it is necessary to enable the service with your SIM card provider in a similar way to how you enable SMS, Voice and GPRS data services. Most SIMs come pre-configured allowing Voice SMS and GPRS but you can switch these services on and off as required. CSD is more usually disabled as a service and is usually switched off by default. You will have to request that the CSD service is turned on before starting CSD on your device.
In addition, some SIM providers offer a dedicated data number for CSD and a dedicated voice number for voice but it is also quite normal to have a single number to provide both services. When using a SIM which supports both services over a single number then the type of call being established can be controlled directly by AT commands on the modem and you can specify a voice or data call for the modem.
The following table shows the typical services available for a modern SIM card and what services are generally turned on by default.
Name Description Default Notes
Voice Make and receive calls x Available on 2G/3G only
SMS Short messaging service x Available on 2G/3G only
MMS Multimedia message service Available on 2G/3G only
CSD Circuit switched dialling Available on 2G/3G only
GPRS Send and receive digital data x Available on all technologies
Fixed Private IP Allocated IP fixed on private network Available on all technologies
Fixed Public IP Allocated IP fixed on public network Available to all
IMS VoIP Voice over LTE (VoLTE) x Available on LTE only
IMS SMS SMS over LTE x Available on LTE only
CSD Dial
Most recent headlines
05/01/2027
Worlds first 802.15.4ab-UWB chip verified by Calterah and Rohde & Schwarz to be ...
04/08/2026
Dalet, a leading technology and service provider for media-rich organizations, t...
04/07/2026
April 7 2026, 19:00 (PDT) Detective Conan: Fallen Angel of the Highway Opens in...
04/06/2026
Sony Electronics is introducing the SRG-AS10, a 4K 60p-compatible PTZ auto-frami...
04/06/2026
This recent grad from Spring, TX, led creative-video output for the Aggies' men's basketball team last season and has been producing video and creating ...
04/06/2026
For the first time at a women's golf major, every player in the field will r...
04/06/2026
Three Panasonic PT-RQ45 40,000-lumen 3-Chip DLP projectors made their first live...
04/06/2026
Bitmovin and Akamai have announced a collaboration with NRJ Group, a French mult...
04/06/2026
Telestream will exhibit at InfoComm 2026 (Booth N7952), demonstrating media work...
04/06/2026
Sony has announced the development of RIALTO 65, a 65mm format image sensor block for the VENICE 2 digital cinema camera, targeting release in the first half of...
04/06/2026
KOKUSAI DENKI Electric America will exhibit at InfoComm 2026 (Booth N8025, June ...
04/06/2026
Bell Media's TSN and RDS are the exclusive Canadian broadcasters of FIFA Wor...
04/06/2026
The Challenge: Receiving Heavy Media Files From Road Games Quickly and ReliablyT...
04/06/2026
MASV, a managed file transfer platform used in broadcast and live sports product...
04/06/2026
NESN has announced the appointment of Fahad Haider as Vice President of Operations and Engineering. Haider returns to NESN, where he previously served as Vice P...
04/06/2026
David J. Halberstam, who spent almost 50 years in sports as a broadcaster and an executive, died June 2 after a years-long battle with brain cancer.
Over his l...
04/06/2026
Although collegiate production programs are tasked with delivering high-quality ...
04/06/2026
California studio, two production trucks, global distribution system are combine...
04/06/2026
New global program empowers and supports storytellers through scriptwriting course and access to industry experts
TikTok and Sundance Institute today announce...
04/06/2026
Steinberg DAWs now boast in-depth Tonalic integration
Celemony's innovative virtual session musician plug-in has just received an update that brings ARA...
04/06/2026
Get Hands-On With Over 20 Mic Brands
GearExpo UK is fast approaching, and if you've been looking for a chance to check out some new mics, then you'r...
04/06/2026
Combos feature new Amplifier Intelligence engine
Positive Grid's latest release sees the company introduce two new combo amplifiers that promise to offe...
04/06/2026
Is Your Job Making You Work this June?
4 June, 2026
Media releases
SBS Launches the World Cup Watchers' Rights Association to Stand Up For Australians&...
04/06/2026
Statement regarding unauthorised use of SBS logos on third party social content
4 June, 2026
Media releases
SBS has become aware of social media posts in c...
04/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
04/06/2026
Bitmovin, a leading provider of video streaming infrastructure, and Akamai, the cybersecurity and cloud computing company that powers and protects business onli...
04/06/2026
American Underground (AU), the Startup Hub of the South and a community of mor...
04/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
04/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
04/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
04/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
04/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
04/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
04/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
04/06/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
04/06/2026
NVIDIA and Microsoft Reinvent Windows PCs for the Age of Personal AI
Brie Clayton June 3, 2026
0 Comments
RTX Spark - a 1-Petaflop Superchip, the Full...
04/06/2026
Inside the Peaky Blinders: The Immortal Man Grade
Brie Clayton June 3, 2026
0 Comments
Simone Grattarola discusses shaping the look in DaVinci Resolve...
04/06/2026
Cine Gear Expo Announces 2026 Awards of Excellence Recipients
Brie Clayton June 3, 2026
0 Comments
Ed Lachman ASC, Caleb Deschanel ASC, and M. David M...
04/06/2026
St. Vincents Live with Orchestra Tour to Feature Berklee Alum Ruby Plume Berklee alumni St. Vincent and Ruby Plume will appear on the same bill across seven d...
04/06/2026
Back to All News
All the Truth in My Lies Coming to Netflix on August 28
Entertainment
04 June 2026
GlobalSpain
Link copied to clipboard
Download the imag...
04/06/2026
Back to All News
Larry Tanz, VP of Content, EMEA, Delivers a Keynote Speech at ...
04/06/2026
Back to All News
Turn Your Living Room into a Stadium With the New FIFA World ...
04/06/2026
Keeping conversations real on LinkedIn Published on Jun 4, 2026 Categories: Product News
LinkedIn Corporate Communications
Share
LinkedIn
Facebook ...
04/06/2026
BackStory follows four Irish young people as they travel back to their parents' homelands
Modern Irish identity is enriched by cultures and influences from...
04/06/2026
June's forecast with GeForce NOW: 100% chance of gaming.
GeForce NOW is lining up new adventures for the month, from big-name blockbusters to quirky indies...
03/06/2026
SES and Viva, Mexico's ultra low-cost airline, have launched multi-orbit satellite inflight connectivity on Viva's Airbus aircraft. A total of 60 A320s ...
03/06/2026
The College Football Playoff, ESPN, and TNT Sports have announced kick times and...
03/06/2026
RED Digital Cinema will exhibit at Cine Gear Expo 2026 (Booth 33, June 5-6, Universal Studios Lot), hosting three panels and hands-on product demonstrations.
P...
03/06/2026
Roku has announced the Soccer Zone, a dedicated hub for FIFA World Cup 2026 content available across the United States, Canada, Mexico, Brazil, Colombia, Argent...
Applicable Products Part number Description 
