A method, computer readable media and a system for determining a Voice over LTE (VoLTE) codec is presented. In one embodiment a method includes discovering a packet header size used in a session using a Silence Insertion Descriptor (SID); inspecting downlink packet sizes coming into a receive buffer; determining when three consecutive packet sizes are greater than zero, then setting a first factor, a second factor, and a third factor equal to zero; calculating a header size; and determining a voice encoding codec by subtracting a header overhead value from the packet size.