[SIPForum-discussion] Standard SIP Replies

[Dale R. Worley]

Adnan Aziz <chaudhryadnan at gmail.com> writes:
>    1. Is it in SIP specification/standards to respond to the OPTIONS
>    packets from REGISTERED and UNREGISTERED users?

The standard is that a device responds to all OPTIONS requests.  Some
devices restrict what senders they respond to.

>    2. Is it in SIP specification/standards to respond to the INVITE packets
>    without any prior REGISTRATION?

The standard is that a device responds to all INVITE requests.  Some
devices restrict what senders they respond to.

>    3. Does the SIP standard also support the registration process using
>    INVITE packets instead of REGISTER packets?

There is no registration process using INVITE requests.

> I shall be very thankful to you for your replies. Also please mention the
> rfc or other authentic reference to support the answers.

See RFC 3261 for explanations of these.

Dale