In the optical transport (core) area of the telecoms network the use of compatible transceivers has yet to gain traction. However in the area of legacy SDH or DWDM networks then transceivers can be hard to obtain because they are no longer produced and have been declared end of life or because of long lead times or ordering difficulties. TXO Optics heritage is in such legacy SDH and DWDM networks and consequently we have broad experience across such platforms as Marconi SDH, Nortel, Siemens, Ericsson, Alcatel, Lucent and so on.