[Spce-user] Using REFER method for transfer

[Ali Ardestani]

*Please find comments after each step*


On Wed, Sep 19, 2012 at 9:06 AM, Jon Bonilla <jbonilla at sipwise.com> wrote:

> El Wed, 19 Sep 2012 17:47:35 +0200
> Imanol Pardavila <imanol.pardavila at ibercom.com> escribió:
>
> > Hi,
> > I've just started testing sip:provider CE, and I have my first question.
> > When I try making a transfer for my endpoint, I get a Forbidden message.
> > As I can see in the pcap file, it seems that sip:provider CE doesn't
> > allow REFER method. Can it be enabled on any config file?
> > Thanks
> > Imanol
>
>
> You can enable it if you want. It's disabled by default to avoid fraud as
> if
> the refer is forwarded to your pstn gws and they accept that method,
> customers
> can receive a local call, be transferred to an international destination
> and
> the peer gw owner pays the bill. Be careful with enabling REFER method!
>
> What can you do to enable it:
>
> - First, you'll need to enable the method itself in the proxy configuration
>   using a customtt template. In kamailio.cfg file add it to the list of
> allowed
>   methods:
>
> -if(is_method("INVITE|ACK|CANCEL|BYE|OPTIONS|PRACK|UPDATE"))
> +if(is_method("INVITE|ACK|CANCEL|BYE|OPTIONS|PRACK|UPDATE|REFER"))
>
> That would be enough for the proxy as REFER is only sent in-dialog and no
> further confguration would be needed.
>
>
*This one worked fine*



> - The second part is that you need to whitelist some headers in sems sbc in
>   order REFER to work. Sems has a list of allowed headers and removes the
> rest.
>   In ngcp.sbcprofile.conf you could disable header filtering or add the
> needed
>   headers to the whitelist:
>
>
> -header_list=P-D-Uri,P-Preferred-Identity,P-Asserted-Identity,Privacy,Allow,Supported,P-Out-Socket[%
> IF kamailio.proxy.presence.enable == "yes"
> %],Event,Expires,Subscription-State,Accept[% END %]
>
>
> +header_list=P-D-Uri,P-Preferred-Identity,P-Asserted-Identity,Privacy,Allow,Supported,P-Out-Socket[%
> IF kamailio.proxy.presence.enable == "yes"
> %]Expires,Accept[% END %], Refer-To, Subscription-State, Event
>

*I change this one like this and it still did not work, looked like some
commas were missing*
*
*
*header_list=P-D-Uri,P-Preferred-Identity,P-Asserted-Identity,Privacy,Allow,Supported,P-Out-Socket[%
IF kamailio.proxy.presence.enable == "yes" %],Expires,Accept[% END
%],Refer-To,Subscription-State,Event*
*
*
*It gave me 500 server errors*
*
*
*
*
*Could you please let me know how to disable filtering all together?*


>
> That should be enough. This has be written without checking so I don't
> warranty
> the result. Maybe I forgot some headers but a ngrep capture could help you
> dealing with that.
>
> I also don't know the result or impact of the billing process when a call
> is
> ended due a REFER.
>
> And please, take in consideration the security risks before enabling this
> method. Make sure your gws don't allow REFER.
>
>
>
> cheers,
>
> Jon
>
>
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>
>


-- 
-- 
Ali S Ardestani
Telephony Systems Engineer
Private National Mortgage Acceptance Company (PennyMac)
6101 Condor Drive
Moorpark, CA 93021

(805) 330-6004 Office
(818) 224-7442 x2654 Office
(626) 817-3512 Mobile
(818) 224-7397 Fax

ali.ardestani at pnmac.com
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