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
11/12/2025
Dalet, a leading provider of cloud-native, end-to-end media workflow solutions, ...
28/11/2025
The Professional Fighters League is looking to super-serve fans of mixed martial...
28/11/2025
Fubo has released in beta on select Roku devices a new feature that lets users display up to four simultaneous streams at once....
28/11/2025
The WNBA playoffs and Week 4 of the NFL regular season highlight the list of live sports events airing on television this weekend....
28/11/2025
The 32nd class of honorees to the B+C Hall of Fame took to the stage at New York's Ziegfeld Ballroom on September 26 for a gala induction event. Click below...
28/11/2025
We hold in our hands the very last Next Text for Next TV, the weekly back-and-fo...
28/11/2025
DirecTV said it made a deal with EchoStar to buy EchoStar's video businesses, including satellite-TV provider Dish TV and virtual MVPD Sling TV, for $1 plus...
28/11/2025
The Broadcasting+Cable Hall of Fame, the premier industry event paying tribute to the influencers, innovators and shining lights of broadcast, cable and streami...
27/11/2025
LONDON Vizrt has added several AI-driven advanced features offering improved speed, intelligence and accuracy in the newest version of its media asset managemen...
27/11/2025
Prime Video has launched AI-powered video season recaps in a beta version for select English-language Prime Original series in the U.S., a move Amazon is callin...
27/11/2025
27 Nov 2025
GSMA brings M360 Eurasia 2026 to Samarkand in partnership with VEON...
27/11/2025
Tahar Rahim and Izuka Hoyle star in the gripping six-part Sky Original from Acad...
27/11/2025
Thursday 27 November 2025
Sky Arts Reveals the Nation's Greatest Basslines - and Queen Reign Supreme
The UK's most iconic basslines have been revealed...
27/11/2025
Back to All News
Stranger Things 5': Prepare for One Last Adventure With O...
27/11/2025
The media industry has a paradox at its core. It's an industry built on light, color and imagination, yet behind the scenes, it's powered by one of the ...
27/11/2025
Rating reflects rating progress across areas including policies, diversity & inclusion, health & safety and Net Zero leadership
Winchester, UK, 27 November 202...
27/11/2025
What are the industry standards for Retail Media? Kathryn explains that certification is based on the IAB Europe Retail Media Measurement Standards and the IAB ...
27/11/2025
World champion boxer and Irish sporting icon Katie Taylor will be in studio this...
27/11/2025
Roblox, one of the world's most popular online gaming platforms for primary ...
27/11/2025
Black Friday is leveling up. Get ready to score one of the biggest deals of the season - 50% off the first three months of a new GeForce NOW Ultimate membership...
26/11/2025
SVG Sit-Down: Prime Video EP Mike Muriano Previews Massive Black Friday Slate Fe...
26/11/2025
A cinematic snow sculpture at the 1995 Sundance Film Festival. Photo by Randall Michelson...
26/11/2025
Book podcasts are booming. On Spotify, you'll find everything from celebrity book clubs to deep dives with bestselling authors. And in markets where audiobo...
26/11/2025
Mumbai, November 24, 2025: In a first-of-its-kind initiative, JioStar, in collab...
26/11/2025
LONDON Factual content producer ITN Productions has launched a new low-latency IP gallery for news bulletins....
26/11/2025
MIAMI TelevisaUnivision said it struck a new multiyear distribution agreement with YouTube TV that includes distribution of TelevisaUnivision's U.S. network...
26/11/2025
OpenDrives, Inc., a leader in software-defined data storage and data services, today announced the launch of the Atlas Corporate Creative Solution. This new Atl...
26/11/2025
Disguise, the industry-leading company powering the world's biggest live performances, is partnering with pioneering LED wall manufacturer DVS to give atten...
26/11/2025
HighField AI, the pioneer in agentic and multimodal automation for broadcast and media production, today announced the expansion of its global channel partner n...
26/11/2025
As high-stakes Premier League fixtures approach and additional premium content launches, with MONO positioning themselves to dominate Thailand's sports stre...
26/11/2025
Hosting a wide variety of events from high-intensity NHL games to complex live music concerts and major entertainment productions, Montreal's 21,000 capacit...
26/11/2025
Vizrt, the leader in live production technology revolutionizing viewer engagement and experience, releases AI-driven advances focusing on speed, intelligence, a...
26/11/2025
ITN Productions, an award-winning factual content producer, today launched a new low-latency IP gallery for news bulletins. Responsible for delivering a leading...
26/11/2025
Ikegami reports ongoing advances throughout 2025 in developing and delivering coordinated television production solutions that maximize quality, versatility and...
26/11/2025
Following the Nov. 21 blackout of NBCUniversal channels on Fubo, the two sides have traded barbs about their inability to reach a new carriage deal....
26/11/2025
LONDON As TV sports rights become increasingly important for both broadcasters and streamers, Ampere Analysis predicts global investment in the genre will surpa...
26/11/2025
LOS ANGELES Vubiquity said it has achieved the Amazon Web Services (AWS) Media & Entertainment Competency as part of the AWS Partner Network (APN). This designa...
26/11/2025
WASHINGTON The Federal Communications Commission's Enforcement Bureau said it has entered into a consent decree with Comcast calling for the cable company t...
26/11/2025
Berklee Named to the Hollywood Reporters Top Music Schools List The publication highlights the college's screen scoring program, industry partnerships, and ...
26/11/2025
Back to All News
Animated Series Love Through a Prism' Casts New Light on ...
26/11/2025
Back to All News
NALIP Unveils Fifth Cohort of Director Incubator
Social Impact
26 November 2025
United States
Link copied to clipboard
The National Assoc...
26/11/2025
YouView Achieves Greenly Gold Certification for SustainabilityNov 26, 2025
YouView is proud to announce a Gold Certification award from Greenly for our perform...
26/11/2025
Back to All News
Netflix Deepens Partnership with Taiwan's 62nd Golden Hors...
25/11/2025
Tracy Bonareri Onchoke, an investigative journalist from Kenya is the winner of the Thomson Foundation's Young Journalist Award 2025.
The 26-year-old-sele...
25/11/2025
SVG All-Stars: Blayke Scheer, Senior Director, Creative Content, YES NetworkThe Indiana alum has turned storytelling into an artform for more than two decadesBy...
25/11/2025
Op-Ed: With FCC's C-Band Auction on the Horizon, Broadcasters Need Proven, C...
25/11/2025
Analysis: Is Baller League really the future of sport? By Callum McCarthy, Editor-at-Large
Tuesday, November 25, 2025 - 10:10
Print This Story
With KSI on...
25/11/2025
Platinum Whitepaper: The Growth of Broadcast in the World of Major Large Scale E...
25/11/2025
SVG Summit 2025 Preview: SVG Women's Sports WorkshopBy Samantha Gabay
Tuesday, November 25, 2025 - 10:27 am
Print This Story | Subscribe
Story Highlig...
Applicable Products Part number Description 
