What are the possible values of “prot” parameter of “SecurityClient” header in a SIP Request?

Question

What are the possible values of prot parameter of SecurityClient header in an SIP Request?

Example:

Security-Client: ipsec-3gpp;prot=<?>

Answer 1

The possible values of “prot” parameter are “ah” , “no” ,”esp”

Example : prot=ah, prot=no, prot=esp