The paper captures how Circuit Emulation enables telecom operators to translate legacy systems using TDM signals such as E1/DS1, E3/DS3, STM-n/OC-n to appropriate packet formats, and carry them on a modern packet transport network. It also demonstrates how Tejas Circuit Emulation Service (CES) cards have one of the most advanced implementations of the circuit emulation function in the industry today. This paper provides an overview of Circuit Emulation technology, compelling reasons for legacy systems to upgrade, and how CEM products from Tejas Networks can help with a smooth transition to ensure a resilient and high-performance deployment.