[Spce-user] Fwd: Re: Blacklist t.38 fax codec

[Daniel Grotti]

Could be,
as I see also the normal t38 negotiation is client-dependent....it

But from RFC3261:

 During the session, either Alice or Bob may decide to change the
   characteristics of the media session.  This is accomplished by
   sending a re-INVITE containing a new media description.  This re-
   INVITE references the existing dialog so that the other party knows
   that it is to modify an existing session instead of establishing a
   new session.  The other party sends a 200 (OK) to accept the change.
   The requestor responds to the 200 (OK) with an ACK.  If the other
   party does not accept the change, he sends an error response such as
   488 (Not Acceptable Here), which also receives an ACK.  However, the
   failure of the re-INVITE does not cause the existing call to fail -
   the session continues using the previously negotiated
   characteristics.



Daniel




On 06/20/2014 02:08 PM, Matthew Ogden wrote:
>
> I think the problem is, a 488 will stop the call altogether?
>
>  
>
> I cant recall, but if you get a 488 in a REINVITE, will the call not
> terminate after that, or does it "failback" to leaving t38
> un-negotiated... might be device dependent?
>
>  
>
> *From:*spce-user-bounces at lists.sipwise.com
> <mailto:spce-user-bounces at lists.sipwise.com>
> [mailto:spce-user-bounces at lists.sipwise.com
> <mailto:spce-user-bounces at lists.sipwise.com>] *On Behalf Of *Leopoldo
> Iglesia
> *Sent:* 20 June 2014 01:55 PM
> *To:* spce-user at lists.sipwise.com <mailto:spce-user at lists.sipwise.com>
> *Subject:* Re: [Spce-user] Fwd: Re: Blacklist t.38 fax codec
>
>  
>
> Ok. "has_totag" where is located ??
>
> El 20/06/2014 13:35, Daniel Grotti escribió:
>
>     I have nothing ready to give you right now.
>     Basically on kamailio proxy you should match a Re-invite (using
>     the "has_totag") and check if SDP contains t38 headers/codec (just
>     have a look how the T38 reinvite looks like).
>     So, if you receive a re-invite with T38 headers into SDP, just
>     send back a 488 reply.
>
>     Daniel
>
>
>
>
>
>     On 06/20/2014 01:28 PM, Leopoldo Iglesia wrote:
>
>         Fine, how can I do this hack? cause endpoints is impossible to
>         mod config, so they are rented and provisioned by an ftth
>         operator.
>
>         El 20/06/2014 13:23, Daniel Grotti escribió:
>
>             Hi,
>             I think you need to avoid to forward the T38 Re-INVITE, so
>             you should hack your SPCE in order to reply to the T38
>             re-invite with a "488 Not acceptable here", for example.
>             So the sender SHOULD fallback to G711.
>             Anyway, the best solution if you have endpoint with t38
>             enabled but they don't work well, is to disable t38.
>
>
>             Daniel
>
>
>
>             On 06/20/2014 01:15 PM, Leopoldo Iglesia wrote:
>
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>                 > But both endpoints support it, that is the problem
>                 and the only > scenario when it fails, so i want SPCE
>                 not to send Fax negotiation to > endpoint,.
>
>
>
>                  El 20/06/2014 12:12, Daniel Grotti escribió: >> Hi,
>                 >> that's strange, if one of the endpoints try to
>                 switch to t38 and the >> other endpoint doesn't
>                 support it, they should fallback to G711. >> >> Daniel
>                 >> >> >> >> >> >> >> On 06/20/2014 01:33 AM, Leopoldo
>                 Iglesia wrote: >>> How can I, blacklist t.38 to avoid
>                 endpoints to try t38 negotiation? >>> >>> When i call
>                 from ericcson ont to fax capable endpoint, it try to
>                 >>> connect t38 fax and There is no voice. >>> >>>
>                 Thanks >>> >>> Leopoldo iglesia >>> >>>
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