We aim to address most questions in the frequently updated FAQ section below. If you can’t find what you’re looking for, feel free to contact us directly by email via
FAQ - Frequently Asked Questions
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Topic 1: Installation and Operation
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Question: For my project I need to connect to a P2M module located in a quite unpopulated area. How can I figure out, if a specific target geo position is covered by a mobile network?
Answer: As a starting point, the GSM Association (GSMA - Global System for Mobile Communications) provides network coverage maps for each country in the world, broken down by technology (GSM, LTE, etc.) and network operator: https://www.gsma.com/coverage/ On top of this, some tools can provide further information about nearby network access points (cell towers), For example, iPhones users can try this app: https://apps.apple.com/de/app/cellular-tower-signal-finder/id6470660460
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Question: I have installed my SMSwatchdog* on-site and set it up for an alarm-protected door that should not be opened. How can I verify that the installation is working correctly ?
Answer: First of all you should verify that your SMSwatchdog is starting up properly after power-up and successfully connects to a mobile network. Refer to the SMSwatchdog User Manual explaining the installation procedure in detail: http://heins-iot.com/wp-content/uploads/2025/07/SW2-User-Manual_eng.pdf . A proper installation is indicated by the built-in LED flashing every few seconds. Additionally, ensure that the network connection meets the required signal quality. For this purpose, use the 'cinfo' SMS command and check returned CSQ value (refer to the SMSwatchdog User Manual). Avoid CSQ levels < 5 .
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Question: I have installed my SMSwatchdog* on-site and verified that the network connection is okay (CSQ = 23). But I rely on proper operation at any time, so I would like to make sure that it will send an alarm SMS in case of a real event. So, how can I verify occasionally that everything still works fine?
Answer: Use the 'astat' SMS command to retrieve the current SMSwatchdog* channel status. At the same time, it serves as a ‘heartbeat’ signal, confirming that the device is active and the network connection is stable. Refer to the SMSwatchdog User Manual for further details: http://heins-iot.com/wp-content/uploads/2025/07/SW2-User-Manual_eng.pdf
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Question: I am sending an SMS command to an installed SMSwatchdog* , but it doesn't respond with an SMS to my phone. Instead, the built-in status LED turns on and stays on. What could be the issue?
Answer: The LED behavior indicates that the SMSwatchdog* received your SMS command and is attempting to send a response, but the network is rejecting the message—most likely because the provider cannot charge for the service. This often happens with prepaid SIM cards that have run out of credit. If you're using a prepaid SIM, you may need to top it up.
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Topic 2: Module Hard- and Software
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Question: Can I add or modify the embedded software of a SMSwatchdog* somehow?
Answer: No, typically not. SMSwatchdog* modules are standard products which are offered as a "black box" with a fixed set of functions and an API for integration purposes. But customer-specific hard- and software modifications are available on request. Please contact:
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