Analog Modem-to-Cellular Converters Information

Analog Modem-to-cellular Converter Analog modem-to-cellular converters allow legacy equipment with built-in analog modems to connect to cellular data networks by emulating the traditional dial-up PSTN network. These devices represent a cost-effective means of updating telecommunications networks to enable landline equipment to communicate with modern wireless systems. In order to interface with legacy equipment, analog modem-to-cellular converters often include integral ports for registered jacks (RJ) and serial equipment. Additionally, they are often fitted with LED's or other status indicators. 

Analog signals are functions that are continuous in the time domain. This means that a graph of the signal versus time does not show any abrupt step change or any discontinuity. These signals are the prevalent signals found in nature. Examples of these types of signals are voltage, sound, voice or temperature, where their representation looks like the following graph: 

Analog signals These signals work very well with analog systems and normally do not need further conversion or conditioning. Modern network systems, however, are designed to work with digital or discrete signals.

A digital signal normally is a representation of an analog signal that has been conditioned or converted using a particular protocol. An example of this is an analog signal using Pulse Code Modulation (PCM), a very important protocol used in the mobile industry. 

The conversion takes place by the use of an Analog-to-Digital Converter (ADC),  an electronic circuit that converts analog signals to digital signals. Once the signal is converted it is transmitted either wirelessly or by wires, normally using a cellular modem that can be integrated into the analog modem or external to it. 

The form factor of the device varies from a simple integrated circuit (IC) to a full desktop module. 


There are many types of devices that perform this operation. The types are based on the protocol and/or the telecommunication network that system uses.

  • 3G is the third generation of mobile communication technology.  The transfer rate of 3G is at least 200kbps, and standards that meet the IMT-2000 (International Mobile Telecommunications.)
  • 4G is the fourth generation of mobile communication technology. The transfer rate for this technology are specified at a peak of 1Gbps. This technology is also known as IMT-Advanced
  • 5G is the next generation of mobile technology that is expected to go beyond the 4G technology by providing data raated of several gigabits per second
  • Global System for Mobile Communications (GSM) is an European standard for the 2G technology. This is the default global stardard for mobile phones.
  • Code Division Multiple Access (CDMA) is a technology used in high frequency cellular phones of 800 MHz to 1.9 GHz bands.
  • Ethernet is a local area network (LAN) protocol that uses a bus or star typology and supports data transfer rates of 10 Mbps. The Ethernet specification is the basis for the IEEE 802.3 standard, which specifies the physical and lower software layers. To handle simultaneous demands, Ethernet uses carrier sense multiple access / collision detection (CSMA/CD) to monitor network traffic.

The classification of the types of these devices is based on the form factor. The form factor of the device varies from a simple integrated circuit (IC) to a full desktop module.


Important specifications include network type, data rate and types of ports.


The network or protocol used by an analog modem-to-cellular converter can idetified by its type such as 3G, 4G, 5G, GSM, CDMA, or Ethernet. Other network options include Integrated services digital network (ISDN) which is an international communications standard for sending voice, video, and data over digital telephone lines or traditional telephone lines. ISDN uses a packet-switching technology and supports data transfer rates of 64 Kbps. There are two basic types of ISDN: basic rate interface (BRI) and primary rate interface (PRI). An additional network option is General Packet Radio Service (GPRS) which is a standard for wireless communications which runs at speeds up to 115 kilobits per second.

Data Rate

The maximum data transfer speed.


  • BNC Connector Bayonet Neil-Concelman (BNC) connectors were designed for military applications, but are used widely in video and RF applications to 2 GHz. BNC connectors are also known as bayonet navy connectors or baby Neil connectors.
  • FireWire® is a cross-platform implementation of the high-speed serial data bus, defined by IEEE 1394, that can move large amounts of data between computers and peripheral devices. FireWire speeds the movement of multimedia data and large files. It also enables the direct connection of digital consumer products such as digital camcorders, digital videotapes, digital videodisks, set-top boxes, and music systems to personal computers (PC).
  • The ISDN BRI S/T interface is used with ISDN networks. 
  • ISDN BRI U ISDN BRI U devices must have a terminator (NT1 terminator) between the ISDN device and the wall jack. The U interface connects NT1-terminated ISDN devices to the telephone company's ISDN wall jack. Many ISDN devices have a U interface for direction connection to the wall jack. 
  • Registered Jack 11 (RJ-11) connectors are standard telephone male connectors used to connected the telephone set to to communication devices. 
  • Registered Jack 45 (RJ-45) connectors resemble standard telephone connectors, but are twice as wide with eight wires. RJ-45s can be used to connect computers to LANs and with phones with many lines.  
  • Serial port or asynchronous serial interfaces are system-to-system communication interfaces in which data is sent over a single wire (serial). 

Image credits:

Multi-tech | Swift.Hg/CC BY-SA 3.0 | ValueTronics


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