Employed in sending data across Ethernet and telephone
The earliest of transceivers were created for Gigabit Ethernet networks and were liked for their hot-swappable abilities similar to the newer SFP devices of today. GBIC, or Gigabit Interface Converters, allowed networks the chance to send information across copper or fiber-optic channels, making for a more versatile device than transmitters and receivers. A major drawback experienced by these GBIC modules was that their size and compatibility problems limited them, eventually paving the way for the XENPAK modules that granted better compatibility for networks.
An advantage of XENPAK transceivers was that they allowed for more configuration standards for Gigabit Ethernet than GBIC modules could provide. Unlike GBIC modules that sent information across either copper or fiber optic channels, XENPAK devices included support for both networks, creating a better, more flexible module. Not only did this device provide better assistance, it allowed Ethernet standards to send data across short and long distances without the need of having several GBIC modules. Single-mode configurations create a single ray of light that transmits information across long distances, while multi-mode configurations are employed to create various signals across short distances. Both single and multi-mode fiber optics were employed by networks, producing the XENPAK device ideal.
10 Gigabit Ethernet
When 10 Gigabit Ethernet came around, XENPAK devices became obsolete because of the newer X2 and XPAK modules that XENPAK gave birth to. These newer devices were smaller and were capable of supporting the same features but at different wavelength setups and over longer distances. When newer SFP transceivers, such as Cisco SFP transceivers, came into existence, the competing standards of X2 and XPAK could not continue to dominate the market as they once had. SFP modules granted more configuration standards for networks, allowing for several wavelength and distance options for Ethernet.
As standards evolve, so does the technology that utilizes these standards, making faster, smaller modules for networks to use in sending information. The future of these devices may be uncertain, but what's certain is newer transceivers will come out with better technology than their ancestors.