What is a GSM Modem?
A GSM modem is a wireless modem that works on a GSM network. Believe it or not the premise behind a GSM modem is not all that different from the old-school dial-up modems. Like standard dial-up modems, a GSM modem uses the standard AT commands to connect and communicate. A dial-up modem uses a fixed (wired) telephone line to transmit data. A GSM modem uses a wireless network (also known as a cell network) to transmit the data. GSM modems come in a variety of "flavors". A GSM modem can be external and connect to the PC via an ethernet connection, via a serial port, or via a USB port.
GSM Modems function using a wireless subscription, just as a cell phone is associated with a specific telecom carrier and service. As far as the wireless/telecom carrier is concerned a cell phone and GSM modem appear identical. In fact, in some cases you can use a cell phone connected to a computer and running a specific application to simulate and behave exactly like a GSM modem (see NotePage's Android SMS Gateway Application).
When a GSM modem is connected to a computer, the computer can use the modem to communicate and pass SMS or text messages over the mobile network. The benefit to using a GSM modem is that you do not need to rely on an Internet connection to send the SMS or text messages. This is particularly useful if the text messages are relaying information about network outages or even in an emergency situation, when network infrastructure may be compromised. The other benefit to using a GSM modem for sending messages, is that you do not need to track the telecom/ wireless carrier associated with each cell phone that you are sending messages to. You simply need the cell phone number of the device you wish to send the text message to.
In addition to GSM modems, another type of cellular hardware that can be used to pass text or SMS messages are GSM routers. The GSM router is connected to the network and functions in the same manner that a GSM modem does
What is Cellular Hardware?
Cellular Hardware is a broader term and while it includes GSM modems it includes others as well. Like a GSM Modem, Cellular Hardware is a cellular modem is a device that works on cellular networks (GSM, CDMA, GPRS, etc) and connects to computers via USB or RS-232. Similar to GSM modems the cellular modems are not all that different from old-school dial-up modems. Like standard dial-up modems, most cellular modems use a variation of the AT command set, though there are some that use their own command language. Where a dial-up modem uses a fixed (wired) telephone line, a cellular modem uses wireless cellular networks to transmit and receive data.
Cellular modems are typically easier to use with physical computers but can also be virtualized. The cellular modem is setup to be accessed by virtual computers. Typically speaking, if you want to use cellular hardware with a virtual machine, you will want to use a cellular router or cellular gateway. Cellular Routers and Gateways are designed to be used with Telnet and SSH instead of relying on a physical connection.
Cellular hardware functions using a wireless subscription and is associated with a specific telecom carrier for service, just like a cell phone. As far as the wireless/telecom carrier is concerned, there are few differences between cellular modems and routers and regular cell phones. In fact, in some cases you can use a cell phone connected to a computer and running a specific application to simulate and behave exactly like a cellular modem (see NotePage's Android SMS Gateway Application).
When a cellular modem is connected to a computer or when a system has access to a cellular router/gateway, it can use these devices to send and receive SMS (text messages) over the carrier network. One of the key benefits to using cellular hardware is that the messaging does not rely on an internet connection. The messages are delivered using the cellular network. This is particularly useful for critical messaging, like network outages and emergency situation notifications or when network infrastructure may be compromised.
The other benefit to using cellular hardware to sending SMS is that you do not need to track the telecom/wireless carrier associated with the cell phones you are sending messages to; you would simply need the cell phone number the message is intended for.