Cisco Spa112 not showing mac address in sip registration

[milansuthar84475]

i have Cisco Spa112 and i want to have MAC address in sip registration
this is my contact string 

         contact: "" <sip:1201@216.178.91.19:18823;alias=10.50.8.1~5060~1;x-nat=yes;pv-ip=172.16.1.3;pb-ip=216.178.91.19;pb-pt=18823;transport=udp>

neither its showing in User-agent , 

   user_agent: Cisco/SPA112-1.3.5(004p)

[Dan Lukes]

It's feature request. Contact Cisco sales department.