Applicable Products Part number Description
ZETA-GEP-LTE4 (EU) Low Power LTE Cat 4 European Modem with GPIO and GNSS
ZETA-G-GPRS Entry Level GPRS Modem with GNSS (GL)
ZETA-N2-GPRS Entry Level GPRS Modem (GL)
ZETA-NEP-LTE4 (EU) Low Power LTE Cat 4 European Modem with GPIO
ZETA-NEP-LTEM (GL) Low Power Global LTE Cat M Modem with GPIO
ZETA-NLP-LTE1 (EU) Ultra Low Power European LTE Cat 1 Modem
ZETA-NLP-LTEM (GL) Ultra Low Power Global LTE Cat M Modem
ZETA-N-LTE (EU) High Performance LTE Cat 4 Modem with GPIO
ZETA-NSP-LTE1 (EU) Low Power European LTE Cat 1 Modem
Objective Once a Siretta ZETA modem is powered on, a combination of its 3 LEDs light up, showing different stages of modem connection to a network (default state).
Also, assuming the network connection is achieved, the modem can send a receive AT commands.
If any of the above fails to materialise, a troubleshooting procedure will help to investigate and solve basic issues.
Solution This application note covers the following:
No LED indication
Modem keeps rebooting
Failure to connect to a modem serial port
No response from the modem when using AT commands
No Carrier when dialling Voice/ data calls
Demonstration of Solution LEDs Not Lit
Check the modem has been connected to the correct power supply
Check the power connector is inserted correctly
Check the power has been switched on at the mains
Check the LED functionality has been set with either AT#SLED or AT#GPIO AT commands
Modem Reboot If your Siretta modem keeps rebooting, please check the following procedures:
Check the SIM card has been inserted correctly
Check the power supply is correctly specified or you are using an approved Siretta PSU.
No Serial Connection If your Siretta modem has no serial connection, please check the following procedures:
Check the serial cable has been inserted correctly
Check the serial cable has the correct pin alignment (see below)
Check the modem emulator program has the proper settings (Factory settings = 115200, 8, n, 1)
Check there isn't another program interfering with the communication program
Check there isn't a conflict with communication port access
RS232 Serial Port Interface This connector provides serial RS232 communication between ZETA-xxP modem and the connected equipment. The modem can be configured via the RS232 connection using AT commands as specified in the AT command manual.
Table 15. Pins Usage
Pin Name Usage Status Direction
1 DCD Output from UART that indicates the carries is present Connected OUT
2 RXD Output transmit line of UART Connected OUT
3 TXD Input receive line of UART Connected IN
4 DTR Input to UART and controls DTE ready condition
Connected IN
5 GND Ground
Connected IN
6 DSR Output from UART that indicates the module is ready
Connected OUT
7 RTS Request to Send - Input line of UART that controls hardware flow control
Connected IN
8 CTS Clear to Send - Output line of UART that controls hardware flow control
Connected OUT
9 RI Ring Indicator- Output line of UART that indicates the incoming call condition
Connected OUT
Supported baudrates
>> 2400 >> 38400
>> 4800 >>57600
>> 9600 >>115200
>> 19200 >230400
No Carrier Message If your Siretta modem returns a No Carrier' message upon an attempted call (voice or data), please consider the following possible causes:
If the modem returns Then ask? Action
No Carrier' Is the received signal strong enough? Use AT+CSQ' to check RSSI.
Check signal strength indication. *
Is the antenna connected correctly? Ensure antenna is firmly screwed into place.
No Carrier'
(When trying to issue voice communication) Is the semicolon ( ; ) entered immediately after the phone number in the AT command? Ensure that the semicolon ( ; ) is entered after the phone number in the AT command. (e.g. ATD123456:)
No Carrier'
(When trying to issue data communication) Is the SIM card configured for data/fax call? Configure the SIM card for data/fax calls. (Ask your network provider if necessary)
Is the selected bearer type supported by the called partly? Ensure the selected bearer type is supported by the call party.
Is the selected bearer type support by the network? Ensure the selected bearer type is supported by the network.
If no success, try bearer select type by AT COMMAND: AT+CBST=0,0,3'
Value of RSSI Interpretation
0 to 12 Insufficient or weak
13 to 19 Average
20-31 Good
99 No Signal
Additional Reading Description Author
ZETA Hardware user's manual Siretta
AT command manual Telit
Quick Start Guide Siretta
Post Views: 32
Europe Stories
05/01/2027
Worlds first 802.15.4ab-UWB chip verified by Calterah and Rohde & Schwarz to be ...
01/06/2026
January 6 2026, 05:30 (PST) Dolby Sets the New Standard for Premium Entertainment at CES 2026
Throughout the week, Dolby brings to life the latest innovatio...
01/05/2026
January 5 2026, 18:30 (PST) NBCUniversal's Peacock to Be First Streamer to ...
01/04/2026
January 4 2026, 18:00 (PST) DOLBY AND DOUYIN EMPOWER THE NEXT GENERATON OF CREATORS WITH DOLBY VISION
Douyin Users Can Now Create And Share Videos With Stun...
21/01/2026
Wednesday 21 January 2026
Backing Britain on the global stage: Sky becomes an o...
21/01/2026
Fox Corporation Executives to Discuss Second Quarter Fiscal 2026 Financial Resul...
21/01/2026
Baselight v7 brings colourists and post-houses smarter mattes, faster workflows and deeper control
FilmLight, known for its detailed colour toolset and longsta...
21/01/2026
RT News is pleased to announce the appointment of Jackie Fox as its new Washington Correspondent. Jackie is a multimedia journalist with RT News and has repor...
19/01/2026
Monday 19 January 2026
Sky News reinvents News at Ten for the modern audience with The Wrap
Sky News today announces The Wrap, a bold evolution of its 10pm ou...
19/01/2026
DPA Microphones is striking a new chord in piano miking with the debut of its DPK2015 Piano Stereo Kit, an out-of-the-box, plug-and-play miking solution that ta...
19/01/2026
DPA Microphones will present its 4099 CORE Instrument Microphone and redesigned...
19/01/2026
Trianel relies on Arvato Systems for future-proof data center operations
Moving to the cloud: Arvato Systems implements extensive IT migration project
Migrat...
19/01/2026
Celebrating 21 Years of the RT Choice Music Prize
RT Choice Music Prize
In association with IMRO and IRMA
Irish Album of the Year 2025 - Shortlist Announce...
18/01/2026
January 18 2026, 21:30 (PST) Dolby Cinema Arrives in Bengaluru: Dolby Laborator...
16/01/2026
The start of a new year brings fresh possibilities. Whether you're diving in with big goals or simply setting new intentions, audiobooks can bring inspirati...
16/01/2026
In 2025 we launched the Spotify Partner Program to give creators more ways to tu...
15/01/2026
The SGL Carbon site in Bonn has a long tradition of training. For many years, young talent has been successfully trained here, regularly achieving excellent exa...
15/01/2026
The JEC Composites Innovation Awards annually honor the most innovative and ambi...
15/01/2026
X-energy Reactor Company, LLC ( X-energy ) and SGL Carbon LLC ( SGL ) have signed a 10-year framework agreement to provide graphite for the deployment of X-ener...
15/01/2026
RT is tonight announcing that Mari Hurley has decided to leave her role as RT 's Chief Financial Officer to take up a new position outside RT . Mari will r...
15/01/2026
15 Jan 2026
VEON's Kyivstar Reaches 3.0 million Customers with Starlink Dir...
15/01/2026
Views to free streaming service U grew by 15%, average monthly active users by 23% and registrations by 18%
UKTV's channels achieved record viewing share, ...
15/01/2026
Thursday 15 January 2026
Sky Sports to show Final Stage of inaugural FIFA Women's Champions Cup
Sky and FIFA have agreed an exclusive new partnership whi...
15/01/2026
Thursday 15 January 2026
The official trailer for the second season of Seth Mac...
15/01/2026
Wuppertal January 15, 2026
Riedel RefCam Takes Center Court in German Basketba...
15/01/2026
Arvato Systems Named Launch Partner for AWS European Sovereign Cloud
As a launch partner for the AWS European Sovereign Cloud, Arvato Systems enables customer...
14/01/2026
Staines-upon-Thames, UK, 13th January, 2026 ITV, one of the UKs leading broadcasters, has selected Yospace, the global leader in Dynamic Ad Insertion (DAI), to ...
14/01/2026
Steiger Media's adoption of Calrec's compact Argo M console not only makes its innovative new hybrid truck faster, more efficient, and agile, but also e...
14/01/2026
Press Release: The Boston Globe Names Cartesian a Top Place to Work in 2025
January 14, 2026
News
Cartesian - January 14, 2026 - EINPresswire.com - Sp...
14/01/2026
Comscore and Marcus Theatres Announce Five-Year Extension for Cinema ACE and Ent...
14/01/2026
Comscore and Santikos Entertainment Announce Five-Year Circuit Wide Commitment t...
14/01/2026
Wednesday 14 January 2026
Sky News announces Cathy Newman to lead flagship new political programme
Sky News today announces that award-winning journalist and ...
14/01/2026
The first stamp of An Post's 2026 Stamp Programme, marking 100 Years of Broadcasting, was unveiled at the GPO by Patrick O'Donovan TD, Minister for Cult...
14/01/2026
It's official! Beverley Callard has landed in Carrigstown. The beloved actor, known for her unforgettable roles and iconic screen presence, is joining the c...
13/01/2026
Independent media in Brazil and Colombia is facing an urgent crisis of traditional business models alongside a deteriorating security environment, according to ...
13/01/2026
Luxembourg, December 17, 2025 - SES S.A. ( SES or the Company ), a leading spa...
13/01/2026
Written and executive produced by Steve Lightfoot and Angela LaManna, produced b...
13/01/2026
New updates to Hitmaker Expansion from Celemony and Softube Edit pitch-perfect vocals with Melodyne Essential and get radio-ready guitar tones from Softube...
13/01/2026
Live broadcasts from RT 2FM Breakfast with Carl, Roz & Aisling, RT Radio 1 Tod...
12/01/2026
Spotify's new co-CEOs, Alex Norstr m and Gustav S derstr m, start off the new year with a message of renewed leadership, creative responsibility, and what&#...
12/01/2026
At Spotify, we listen to a lot of music. And every year, our global editors and artist partnerships teams come together to spotlight the emerging voices we beli...
12/01/2026
Spotify's global editors and Songwriter & Publisher Partnerships team spend their days immersed in new music, tracking the writers behind the songs breaking...
12/01/2026
Rohde & Schwarz opens larger office in Japan and increases its support for the J...
12/01/2026
X-Rite and Rhopoint Launch Rhopoint PANTORA Aesthetix to Streamline Creation of...
12/01/2026
12 Jan 2026
VEON's Kyivstar Launches 5G Pilot in Lviv Lviv, January 12, 2026 - VEON, a global digital operator (Nasdaq: VEON), today announces that Kyivsta...
12/01/2026
Monday 12 January 2026
The ultimate betrayal: Harry and Jamie Redknapp, Paul Me...
12/01/2026
Rohde & Schwarz opens larger office in Japan to increase its support for the Jap...
12/01/2026
Welcome to the AVECO team: introducing new members of management
At AVECO, we are continuing to implement our #newAVECO strategy, which aims to build an even s...
12/01/2026
For the first time in the nine-year history of Dancing with the Stars, the first...
Applicable Products Part number Description 
