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I found this with a quick googling (Cisco SIP "Early offer"):
"RFC 3261 defines two ways that SDP messages can be sent in the Offer and Answer. These methods are commonly known as Delayed Offer and Early Offer, and support for both methods by User Agent Client/Servers is a mandatory requirement of the specification. In the simplest terms, an initial SIP Invite sent with SDP in the message body defines an Early Offer, whereas an initial SIP Invite without SDP in the message body defines a Delayed Offer.
In an Early Offer, the session initiator (calling device) sends its capabilities (for example, codecs supported) in the SDP contained in the initial Invite (thus allowing the called device to choose its preferred codec for the session). In a Delayed Offer, the session initiator does not send its capabilities in the initial Invite but waits for the called device to send its capabilities first (for example, the list of codecs supported by the called device, thus allowing the calling device to choose the codec to be used for the session).
Delayed Offer and Early Offer are the two media capabilities exchange options available to all standards-based SIP switches. Most vendors have a preference for either Delayed Offer or Early Offer, each of which has its own set of benefits and limitations."
Obviously "Early offer" simply means that the offer is included in the INVITE, and does not leave it to the UAS to send one.
So, without knowing anything about DUM I would say that it *can* handle early offer, because otherwise it would get in all sorts of trouble ...
Rgds
Mats
-----Original Message-----
From: Scott Godin [mailto:sgodin@xxxxxxxxxxxxxxx]
Sent: Sat 2009-12-19 16:36
To: easassone@xxxxxxxxx
Cc: resiprocate-users@xxxxxxxxxxxxxxx
Subject: Re: [reSIProcate-users] Early Offer
resip/dum has the ability to both process and send an SDP answer early.
This means that the SDP answer that is going to be provided in the 200
response is returned early in a 18x response, and it's repeated later in the
200. Perhaps this is what the Cisco is referring to - but I think Early
Offer is a strange name, since it's really an early answer.
Scott
On Fri, Dec 18, 2009 at 9:29 AM, <easassone@xxxxxxxxx> wrote:
> Hi Scott
>
> Here is what Cisco is telling us that Early Offer is. This for their call
> recording interface that uses SIP trunking. They said this is not in an
> RFC.
>
> *********************************
> Sip Early Offer is the ability of two user agents to communicate before a
> call is actually established. In the case of recording, the SIP Early Offer
> will indicate the codec required for the call.
>
> Thanks
> Ed Sassone
> ------Original Message------
> From: Scott Godin
> Sender: slgodin@xxxxxxxxx
> To: voora srinivas
> Cc: resiprocate-users@xxxxxxxxxxxxxxx
> Cc: Ed Sassone
> Sent: Dec 17, 2009 3:45 PM
> Subject: Re: [reSIProcate-users] Early Offer
>
> What exactly do you mean by Early Offer?
>
>
> Scott
>
>
> On Thu, Dec 17, 2009 at 2:46 PM, voora srinivas <voora@xxxxxxxxx <mailto:
> voora@xxxxxxxxx> > wrote:
> Hi,
>
> Want to know if Dum can handle "Early Offer", i saw some previous threads
> that it can be done, but don't see it in the supported features list.
>
> Thanks,
> Srinivas
>
>
>
>
>
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