Which header fields will a User Agent Client (UAC) use to communicate the SIP extensions, or options, it expects the corresponding User Agent Server (UAS) to support?
A. Require:
B. Supported:
C. Subject:
D. Capability:
E. Features:
Which header fields will a User Agent Client (UAC) use to communicate the SIP extensions, or options, it expects the corresponding User Agent Server (UAS) to support?
A. Require:
B. Supported:
C. Subject:
D. Capability:
E. Features: