Many times, User over a period requires increase in capacity of Trunk as well as Extensions due to growth of Organization. The System have expansion capacity from 206 to 616, the expansion till 308 is done by merely changing Line Card but beyond that, CPU child card is also required so that extra cost burden does not come on smaller System User with open option for future expandability. Many other Brands does not have this option and User compulsory have to change complete System in which older System hardly fetch any discount.