C-52

SIP Phone to PSTN: Call Blocking
Figure C-19. Call Flow DIagram: SIP IP Phone to PSTN: Call Blocking
SIP Phone UA Marshal
1. INVITE
2. 100
Redirect Server
3. INVITE
4. 302
5. ACK
Feature Server:
Call Blocking
6. INVITE
7. 100
8. 403
9. ACK
10. 403