Thank you for correcting, Yes, I mean OPTIONS.
I need to have guaranteed delivery of SIP MESSAGE , but I can’t see any options to do it.
In my case peer - is a mobile phone with sip application, and it can change IP address, or completely disappear at any time. But asterisk will think peer still online until it send next qualify ping and will not get respont.
I am trying to find way to get confirmation of delivery, or at least big chance of it.