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By Lorenzo Raftacco


SMS-GW as part of the Ecosystem Monitoring HW group

The SMS-GW3 Gateway can not only be useful in large monitoring projects with dozens of devices and perhaps hundreds of sensors, but in all cases where people simply prefer to receive an SMS or phone call from the monitoring device instead of an e-mail.
We do not want to judge this kind of approach. Simply, each monitoring project becomes unique by considering how managers prefer to organize the system and alerts in case of anomalies.

That is why HW group produces two versions of the SMS gateway, which we will discuss in detail.

SMS-GW3 is part of the Remote Monitoring Ecosystem (RME).

Sending an SMS message and/or making a voice call to alert the customer if there is something wrong at the remote location is the latest service provided by HWg. This type of alerting should still be able to work reliably five years from now, regardless of what is installed on the customer's cell phone.
It is an easy system to set up, but reliable in the long run, and this is one of the core values for HW Group.

All HW Group products can use SMS-GW3 for SMS alerts and CallOut. It is cheaper and simpler to have one gateway with one SIM card in the company than to rely on an independent SIM with monthly fees on each monitoring device with its sensors.

Diagram - SWS-GW Usage Topology

Both 2G (GSM) and LTE SMS gateways (nowadays there is probably no need to explain the difference between the wireless broadband standards), referred to as SMS-GW3 since it is the third version of the HW group production gateway, perform the same function: to send an alert in the form of a user/device-defined SMS message or to make a call alert, which is basically a call to a destination phone number.

SMS-GW3 works seamlessly with all HWg products without any additional software. An SMS-GW3 on the same LAN can be accessed by multiple HW group devices in the enterprise. It provides the functions of sending SMS and CallOut (ringing) to multiple devices simultaneously and sends alerts through the cellular network.

The SMS-GW3 device can also be used with the SensDesk portal or even with third-party services. Portals based on the SensDesk technology can use SMS-GW3 LTE for sending alerts, provided the gateway is accessible to the portal itself (via a VPN or public IP address): all SMS and CallOut alerts could be handled by the gateway instead of the Twilio software service available for a fee to portal users SensDesk.

Schema - SensDesk with SMS-GW3

However, both options (SMS-GW unit/SMS alert from the Gateway) have limitations and advantages. Using only the gateway unit can cause a situation where the monitoring device is turned off (disconnected): it will not be possible to send a critical alert message or make a call. Therefore, the combination with the SensDesk Portal makes alerts even more reliable.

The following features are shared between the 2G and LTE versions of the gateway:

  1. External antenna with 3 m cable
  2. Internal memory for outgoing SMS queue: 100 messages
  3. SMS/Call GW for all HWg (RME) devices.
  4. GW SMS/Calls for any SNMP software
  5. SMS/Call GW for any NAGIOS (NETWAYS plugin).
  6. Open API: SNMP, XML, netGSM (http, SOAP)
  7. Supports "SMS + Ring" function for combined SMS and CallOut notification
  8. Mechanical: 76 x 93 x 28 mm, wall mountable or DIN rail mountable (optional)

Using SMS-GW from third-party SW/HW.

Third-party devices (or software) can access SMS-GW3 using one of three options:

  1. netGSM (SOAP - POST HTTP)
  3. SNMP writing (sending SMS from any SNMP software)

One of the most convenient features of SMS-GW3 is that the SMS alerts and CallOut themselves are fully customizable within different monitoring devices that use SMS-GW3 as a gateway: easy to connect to devices, especially within the HWg product ecosystem.

Diagram - SWS-GW Usage Topology

Therefore, it is not necessary to have different configurations on the SMS-GW3 device, but everything is simply managed on the different monitoring units with the corresponding sensor sets.

In this way, a single SMS-GW3 can be used to send dozens of SMS or CallOut alerts to an unlimited number of recipients. If, in addition to standard e-mail alerts, you need a faster and, according to some, more reliable option, or simply a slightly different means of sending an alert, SMS-GW3 is here for you, supporting both the newer LTE connection and the older 2G system.

Common question: should I buy a cheaper 2G (GSM) version or better the LTE version?

The old GSM (2G) standard began in the 1990s and is still operational in many countries, but most national regulators have already declared the date when the 2G GSM cellular network will be decommissioned. Switzerland is likely to be the first European country to disable 2G coverage.

However, there are so many devices that depend on this network that it may take a decade for this to happen in your country.


Using a single SMS-GW hardware unit to send alerts (SMS/calls) from multiple LAN sensors in the enterprise makes the entire HWg monitoring system more robust and reliable in the long run, even in a convenient and completely offline (portal-free) manner.


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