Modern telephony systems have become highly technical and deliver a wide range of functions. Often supported by features such as full color displays, they enable advanced connectivity including the ability to maintain hundreds of extensions.
To do this, they need high-performance electronics in conjunction with high-performance processors enabled by DRAM and flash memory.
SDRAM is also still used in some older applications, and DDR3 in conjunction with eMMC flash memory has been adopted in most next generation products.
Telephone distribution systems as used in reception and call centers, take advantage of DDR2 or DDR3 memory modules.