CODEWITHSUNDEEP
sip
Parag Amritkar
Parag Amritkar

Reputation: 111

Is UPDATE allowed before PRACK is not received from the network to the earlier 18x(Reliable Provisional Response)

Invite carries offer from the network. Can we send Update with sdp before the PRACK for first 18x is pending from the network, 18x sent was reliable provisional response?

RFC 3261 says "After the first reliable provisional response for a request has been acknowledged, the UAS MAY send additional reliable provisional responses. The UAS MUST NOT send a second reliable provisional response until the first is acknowledged. After the first, it is RECOMMENDED that the UAS not send an additional reliable provisional response until the previous is acknowledged. The first reliable provisional response receives special treatment because it conveys the initial sequence number. If additional reliable provisional responses were sent before the first was acknowledged, the UAS could not be certain these were received in order."

Upvotes: 1

Views: 1462

Answers (2)

Dinoop paloli
Dinoop paloli

Reputation: 633

As per RFC 6337 section 4.2, UAC should not send update if PRACK is still not received. Even though it is regarding reINVITE, I think it is relevant in your case also

Upvotes: 0

sipsorcery
sipsorcery

Reputation: 30699

PRACK and UPDATE requests are both extensions to the core SIP RFC so there is no guarantee that they will be widely supported. I'd expect support for the UPDATE request in particular to be pretty limited in among various SIP implementations.

Looking at the UPDATE request RFC there is no requirement that PRACK requests be supported or that the UAS must wait for a PRACK before sending an UPDATE request. So the answer to your question is no the UAS does not have to wait for a PRACK before sending any UPDATE requests.

There are rules in the UPDATE RFC that state how UPDATE requests are handled if there are outstanding offers that have been sent in a PRACK request but that's a different thing,

Upvotes: 1

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