This application discloses various techniques for call establishment using voice-over LTE (VoLTE) in networks supporting time division (TD) and frequency division duplexed (FDD) LTE communication systems. Such techniques can include systems and methods for mobile-originated calls for a UE in a TD-LTE cell, systems and methods for mobile-terminated calls for a connected UE in a TD-LTE cell and systems and methods for mobile-terminated calls for an idle UE in a TD-LTE cell. These methods and systems can leverage component carriers from a carrier aggregating capable UE to facilitate more efficient and/or effective UE call establishment.