You can save the prompts in μ-Law or A-Law. While saving a prompt file, ensure that the 8.000 kHz, 8 Bit, Mono 7 kb/sec attribute is selected. (https://<FQDN of UCCX>/appadmin/help/default/appadmin/help/output/index.html#!uccx_r_125record-prompt.html...

SEP stands for Selsius Ethernet Phone, which was the original company that created Call Manager.  Cisco later acquired this company but the SEP from the original company was retained.