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 ...
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...
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...
07/05/2026
Journalists reporting on Sudan are working in one of the most complex and fast-m...
07/05/2026
Seit dem Start im Jahr 2023 hat DJ (Beta) das personalisierte H rerlebnis von 94...
07/05/2026
Da quando stata presentata nel 2023, DJ (beta) ha aiutato a definire un'esperienza d'ascolto pi personalizzata per 94 milioni di utenti Spotify Premi...
07/05/2026
Since launching in 2023, DJ (beta) has helped shape a more personalized listenin...
07/05/2026
Desde o lan amento em 2023, o DJ (beta) j ajudou a deixar a experi ncia de ouvi...
07/05/2026
From our earliest days, Spotify has been built on a simple principle: Great audio should be easy to reach. It's what's driven us to expand from music to...
07/05/2026
Asian and Pacific Islander artists continue to shape the global soundscape, pushing creative boundaries and connecting with fans worldwide. This Asian & Pacific...
07/05/2026
Company announce long-requested choir instrument
In the latest expansion of their Symphonic Elements series, UJAM have introduced an all-new vocal instrumen...
07/05/2026
Modular-inspired sound generation with digital control
Buchla have introduced Ziggy, a new compact synthesizer built around the company's complex oscill...
07/05/2026
Combines analogue voices with digital synthesis and sequencing
Polyend have announced Drums, a new hybrid analogue and digital drum machine that combines sy...
07/05/2026
Control surface now officially supports four DAWs
When Nektar launched the Panorama CS12 control surface, it worked exclusively with Apple's Logic Pro, ...
07/05/2026
In the first quarter 2026, SGL Carbon generated consolidated sales of 184.5 million, which was 49.8 million, or 21.3%, lower than in the prior year (Q1 2025: ...
07/05/2026
Rohde & Schwarz and Greenerwave achieve precise and fast ESA antenna characteriz...
07/05/2026
January 8, 2024
Colorfront (colorfront.com), a leader in high-performance, on-s...
07/05/2026
February 9, 2024
Colorfront (colorfront.com), the multi-award-winning pioneer i...
07/05/2026
March 20, 2024
NAB 2024, Las Vegas - Colorfront (colorfront.com), the multi-awa...
07/05/2026
April 1, 2025
CINEMACON, APRIL 1, 2025 - Colorfront (colorfront.com), the multi-award-winning developer of high-performance dailies/transcoding/streaming syste...
07/05/2026
June 15, 2025
Colorfront (colorfront.com), an Academy and Emmy Award-winning de...
07/05/2026
June 15, 2025
Colorfront participated in the ICTA Barcelona Cinema Technology Summit on Sunday, June 15, 2025. Held at The Phenomena Experience, the event feat...
07/05/2026
July 1, 2025
Colorfront (colorfront.com), the multi-award-winning developer of high-performance dailies/transcoding/streaming systems for motion pictures, OTT,...
07/05/2026
July 1, 2025
Passion and dedication will take you places. Come with us on a short trip to the heart of India, where Annapurna Studios is living-up to the inspi...
07/05/2026
July 3, 2025
Colorfront (colorfront.com), the multi-award-winning developer of high-performance dailies/transcoding/streaming systems for motion pictures, OTT,...
07/05/2026
September 1, 2025
IBC 2025, Amsterdam - Colorfront (colorfront.com) - the Acade...
07/05/2026
April 17, 2026
LOS ANGELES - April 17, 2026 - Colorfront today announced Colorf...
07/05/2026
April 23, 2026
NAB 2026, Las Vegas - the Academy and Emmy Award-winning develop...
07/05/2026
Thursday 7 May 2026
Sky continues Sphere Abacus partnership with The Death of S...
07/05/2026
Thursday 7 May 2026
Sky Confirms Saturday Night Live UK will return this September for Series Two
Saturday Night Live UK will return for a second series, as S...
07/05/2026
Save 20% on the Sky Glass Gen 2 and Sky Glass Air TVsThursday 7 May 2026
How to watch the World Cup on Sky Glass
Tune into the World Cup on the BBC and ITV vi...
07/05/2026
Production sound mixer Dirk Sciarrotta has mixed Family Feud for 28 seasons. Thats up to 200 syndicated episodes per year, plus primetime celebrity specials - a...
07/05/2026
As audience expectations have evolved, Owen has stopped trying to hide microphones or excuse amplification. Instead, he treats sound as a fully immersive part o...
07/05/2026
Well known Irish faces pushed to the edge in new series of
Uncharted with Ray G...
07/05/2026
RT will premiere A Traveller Family, a compelling new documentary exploring the...
06/05/2026
New pricing tiers for vocal/dialogue restoration tool
NoiseWorks Audio's AI-powered vocal and dialogue processing plug-in is now available in three diff...
06/05/2026
Popular mixing & routing software overhauled
Following a recent public beta test, RME have launched the final release version of the powerful mixing and rou...
06/05/2026
New SOS Video Feature
Focusrites ISA C8X is a milestone product that brings together the companys analogue heritage and their expertise in digital audio. Yo...
06/05/2026
06 May 2026
VEON's Kyivstar Authorized to Resell Starlink for Businesses & ...
06/05/2026
UKTV has secured the exclusive rights to the early back catalogue of iconic Australian drama series Neighbours, following a landmark content deal with Fremantle...
06/05/2026
Wednesday 6 May 2026
Sky commissions feature documentary to mark 10th anniversa...
06/05/2026
Wednesday 6 May 2026
Sky and Formula 1 agree long-term partnership across UK, Ireland and Italy
Sky in the UK & Ireland to remain the home of Formula 1 until ...
06/05/2026
Sky Zero Footprint Fund-backed TV campaign launches nationwide, supported by new...
06/05/2026
Wuppertal May 6, 2026
Riedel Expands Leadership Structure, Appoints Marc Engro...
06/05/2026
SAN JOSE, Calif. - May 6, 2026 - Harmonic (NASDAQ: HLIT) today announced its latest broadband innovations for ANGA COM 2026, highlighting its vision for a new e...
06/05/2026
Statement from Rupert Murdoch, Chairman Emeritus, Fox Corporation on Ted Turner&...
06/05/2026
Friday 8 May on RT One and RT Player
Meet the NSPCA team caring for and protecting animals in need in this six-part series
Fly on the wall, six-part series...
Applicable Products Part number Description 
