To disable SIP ALG, run these commands:
#edit
# set security alg sip disable
# commit
Running this command will show if this works:
#run show security alg status
You should see this:
ALG Status :
DNS : Enabled
FTP : Enabled
H323 : Enabled
MGCP : Enabled
MSRPC : Enabled
PPTP : Enabled
RSH : Enabled
RTSP : Enabled
SCCP : Enabled
SIP : Disabled
SQL : Enabled
SUNRPC : Enabled
TALK : Enabled
TFTP : Enabled
IKE-ESP : Disabled