[Serusers] Determine UAS on remote SIP phones

[radan]

Hi all

This question is not connected directly wiht SER but
I didn't find another place. Sorry,

I would like to determine state of UAS ( DND, forward calls
turned on my remote sip phones.
Which tools should I use ? sipsak  ? maybe something else.
When I send options method to remote sip phones I always receive
SIP/2.0 200 OK response regardless of activated call features (DND, 
forward)

How can I distinguish different state of UAS ?

Thansk
radan