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...
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
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 by Patrick O'Donovan TD, Minister for Culture, Com...
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...
10/01/2026
This year, podcasts are making their Golden Globes debut with a new category honoring the medium's leading shows and creators. To mark the occasion, Spotify...
09/01/2026
RT Player has 157 million streams, up 10% year-on-year
An increase on 2024, RT...
09/01/2026
RT 2FM has today announced the highly anticipated list of 2FM Rising Artists for 2026, kicking off 2FM Rising week for the eighth year on The Tracy Clifford Sh...
09/01/2026
RT to Host the 2026 RTS Ireland Awards
Thursday, 16 April 2026 | Dublin Royal Convention Centre
The RTS Ireland Television Awards 2026 | Gradaim RTS 2026 | R...
08/01/2026
An evidence-based analysis on disinformation and information manipulation in Sudan's ongoing conflict is published today. (January 8th 2026).
Thomson Found...
08/01/2026
In 2025 we launched the Spotify Partner Program to give creators more ways to tu...
08/01/2026
On Wednesday in Los Angeles, Spotify welcomed creators and press to a brunch cel...
08/01/2026
TSA awards Rohde & Schwarz contract for advanced airport screening ahead of Socc...
08/01/2026
The review looks back at DPA's miniature microphone development over the years. It compares the evolving technologies from the original mics through CORE an...
08/01/2026
Comscore Launches Audio Targeting and Measurement Capabilities with The Trade De...
08/01/2026
Tonight, on RT Prime Time at 9:35pm on RT One and RT Player
Tonight, Prime T...
08/01/2026
The Late Late Show celebrates the very best of traditional Irish music with its first-ever full special dedicated entirely to the tradition
Lisa Canny | Kevin...
08/01/2026
It will be murder on the dancefloor when Dancing with the Stars returns this S...
07/01/2026
Spotify is launching a week-long celebration spotlighting creators at the center...
07/01/2026
We know people use Spotify not just to listen, but to share the songs, podcasts, and audiobooks they love with their friends and family. When we launched Messag...
07/01/2026
This week, all eyes are on the podcast industry as the Golden Globes recognizes ...
07/01/2026
Podcasts are stepping onto a new stage this week as the Golden Globes recognize the medium for the first time. To mark this milestone moment, we're hosting ...
06/01/2026
Spotify is launching a week-long celebration spotlighting creators at the center...
06/01/2026
Lorde. A$AP Rocky. JENNIE. Baby Keem. KATSEYE. That's just a taste of who...
06/01/2026
Channel 4 and UKTV are giving viewers even more reasons to stream, with UKTV's U service set to feature thousands of hours of free, unmissable and bingeable...
06/01/2026
Tuesday 6 January 2026
An update on our Sky Mobile prices
Devesh Raj, Chief Operating Officer, Sky
Today, we've announced some changes to the prices of ...
06/01/2026
Comscore Launches Daily Program-Level Reporting with Deduplicated Insights on Sh...
06/01/2026
Comscore Completes Recapitalization Transaction with Preferred Stockholders Foll...
05/01/2026
Bad Bunny's DeB TiRAR M S FOToS defined the sound of 2025 for listeners eve...
05/01/2026
As the clock struck midnight and 2026 was born, so was an exciting range of new ...
Applicable Products Part number Description 
