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
Most recent headlines
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...
02/05/2026
Dalet, a leading technology and service provider for media-rich organizations, t...
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...
26/03/2026
Extron and Audio-Technica have announced that their Design Solutions devices, Ce...
26/03/2026
SPORTEL Asia took place March 24-25 at the Orchard Hotel Singapore, drawing 370 participants representing more than 220 companies from 35 countries. Approximate...
26/03/2026
LTN will demonstrate satellite-to-IP migration solutions for broadcasters, cable networks, MVPDs, and station groups at NAB Show 2026 (Booth W2100).
The C-Ban...
26/03/2026
The Seattle Mariners have partnered with Daktronics to install an upgraded outfi...
26/03/2026
The Esports Foundation (EF) has awarded National Team Partner status to organizations and individuals across more than 100 countries and territories for the Esp...
26/03/2026
Telestream has announced expanded integration between its Vantage workflow platf...
26/03/2026
FOR-A Corporation has announced a partnership with Nippon TV and NVIDIA to distr...
26/03/2026
CBS Sports and the WNBA have expanded their partnership through a new long-term, multiplatform rights agreement. CBS Sports will feature up to 20 regular-season...
26/03/2026
Zac Brown Band will star in the Sunday Night Baseball show open on NBC and Peacock, NBC Sports announced. The open was filmed at American Family Field, home of ...
26/03/2026
Major League Baseball opens the 2026 season with nationally televised games across multiple media partners. Fans can visit MLB.com/Watch for a complete schedule...
26/03/2026
DIRECTV has announced an agreement to carry nine new MLB-operated team channels, covering the Cincinnati Reds, Detroit Tigers (Detroit SportsNet), Kansas City R...
26/03/2026
Nationals.TV, the Washington Nationals' local broadcast channel, is now avai...
26/03/2026
Starting Thursday, March 26, MLB.TV will be available on the ESPN App, giving fans access to more than 2,000 out-of-market regular season games. Fans can also r...
26/03/2026
Spotify's partnership with NAVER, Korea's leading digital platform, is built around one simple goal: making it easier for listeners in Korea to discover...
26/03/2026
Exclusive to ComposerCloud for first month
Sample library and virtual instrument gurus EastWest have announced the upcoming release of a new virtual drum i...
26/03/2026
Friday 27 March
Friday 27 March will mark Dynamic Range Day 2026, the annual day of online activity that was started in 2010 by mastering engineer Ian Sheph...
26/03/2026
Includes four separate instruments
Max Richter's SRM Sounds venture have just announced their fifth release, ASMR Choir. Captured at the main live room ...
26/03/2026
The National Film and Video Foundation (NFVF), an agency of the Department of Sport, Arts and Culture (DSAC), has been tasked with administering the Sixth Presi...
26/03/2026
By Matt Klein
Hello to everyone reading this - whether you're a current YEP, HPA member, or just YEP-curious. I'm Matt Klein, one of the co-chairs of t...
26/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
26/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
26/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
26/03/2026
28 participating companies, from start-ups to blue-chips, lead the UK Group as part of the GREAT Britain and Northern Ireland presence across all the Halls at N...
26/03/2026
Arkona Unveils BLADE//planner and Major Usability Enhancements at NAB 2026
Brie Clayton March 26, 2026
0 Comments
New graphical configuration tool and...
26/03/2026
Bitfocus showcases complete control at NAB Show 2026
Brie Clayton March 26, 2026
0 Comments
Continuing development drives advances in security, availa...
26/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
26/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
26/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
26/03/2026
Share
Copy link
Facebook
X
Linkedin
Bluesky
Email...
26/03/2026
Nevion introduces powerful new Panel Builder to enhance VideoIPath broadcast con...
26/03/2026
2026 Oscar Nominated Films Powered by Blackmagic Design
Brie Clayton March 25, 2026
0 Comments
DaVinci Resolve Studio used on 27 of this year's no...
26/03/2026
Leader to present full suite of advanced Test & Measurement solutions at NAB Sho...
26/03/2026
Boston Conservatory to Present New England and Collegiate Premiere of Groundbrea...
26/03/2026
Thursday 26 March 2026
HBO Max included for Sky and NOW customers from 26 March...
26/03/2026
Thursday 26 March 2026
Sky Sets Iconic Costumes Dancing Together Like Never Before' in Brand CampaignTurn on cookies to view this content. Go to Privacy o...
26/03/2026
Wuppertal March 26, 2026
CS live Builds Future-Ready OB Van With Riedel MediorNet and hi Control SystemRiedel Communications today announced that Czech-based ...
26/03/2026
Back to All News
Have a Wish Worth Dying For? Netflix's First Korean YA Hor...
26/03/2026
Back to All News
The Truthers, Starring Jose Coronado and St phanie Magnin, Pre...
26/03/2026
Enhancements to Harmonic's Sports Streaming Solution Introduce Server-Side Multiview, Contextual Metadata-Driven Advertising, Dynamic In-Stream Ads and Robu...
26/03/2026
Open the report
Our 2025 report brings together results from 79 business magazine titles across 22 market sectors, published by 49 media owners. Over the year,...
26/03/2026
Editor's note: This post is part of Into the Omniverse, a series focused on ...
26/03/2026
RT Commercial today announced Fiat as sponsor of The Louise Duffy Show on RT Radio 1, Weekdays 3pm 4pm.
The Louise Duffy Show is the home of daytime music...
26/03/2026
That gaming backlog won't clear itself - GeForce NOW is here to help. Stream the latest titles straight from the cloud across a variety of devices.
This we...
26/03/2026
Wayne, N.J., March 26, 2026 Phantom High-Speed announces the latest product li...
Applicable Products Part number Description 
