You do not use COS for restrictions any more.
COS is the Class of Service of the phone that gives it features - what it can and cant do.
LCOSV - Least Cost Routing Class of Service Voice is the one that restricts or allows the phone to dial local and/or long distance.
Check a phone that can dial out.
DIS-SBCSU:XXXX;
Check what LCOSV it has.
Change another phone to that LCOSV
CHA-SBCSU:STNO=XXXX,LCOSV1=XX;
To see what extensions have what LCOSV
DISPLAY-SBCSU:TYPE=LCOSV,LCOSV=1;
DISPLAY-SBCSU:TYPE=LCOSV,LCOSV=2;
etc.