[Freeswitch-users] att_xfer and loopback

[Dmitry Sytchev]

I asked this question many times on mailing list, and now I'm sure this
can't be really done with loopback.
The only alternative for loopback is to re-inject call into FS via some
separate Sofia profile, and specify that profile in string for att_xfer.
This brings up large amount of troubles including DTMF transcoding,
sequential att_xfer attempt recognition and overall voice/dtmf delay
introduced by chained channels. Maybe some channels can be moved out of
scene by using 'simplify' api on correct channels, but this needs tests.

Anyway, loopback channel in FS is completely unusable, so we do need to
have some  best practices on how to do things without it in FS wiki...
Maybe I have time and will describe our experience soon.

2012/6/4 Michael Collins <msc at freeswitch.org>

>
>
> On Sun, Jun 3, 2012 at 2:15 PM, Avi Marcus <avi at avimarcus.net> wrote:
>
>> I know you can do anything in the dialstring. But intended feature is to
>> allow the user to do an attended transfer to any number that they could
>> reach via the default calling. The default outbound path already has a LOT
>> of stuff set up and it would be impossible to duplicate that within a
>> SINGLE dialstring in a function call.
>> What is needed is for an att_xfer to be able to have leg C hit the
>> dialplan and bridged however a "normal" leg B to that number would be
>> called.
>> Does this make sense?
>>
> Perhaps, but I remain unconvinced that this scenario is impossible without
> loopback. How about the OP actually supply a sample Lua script and dialplan
> and call log? I'd be willing to wager that the gurus could come up with a
> non-evil alternative that actually works. Just because loopback seems like
> a clean solution doesn't necessarily mean that it is. I'll leave it to
> Anthony to give the technical reasons why loopback doesn't always work as
> one would expect or why it should be avoided wherever possible.
>
> -MC
>
>
>>  -Avi
>>
>>
>>
>> On Mon, Jun 4, 2012 at 12:02 AM, Michael Collins <msc at freeswitch.org>wrote:
>>
>>> Au contraire mon frere!
>>>
>>> You can do multiple things in a dialstring, like setting channel
>>> variables. You can also use execute_on_ring/media/answer to execute the
>>> extension with doing all the loopback overhead.
>>>
>>> I propose an experiment: provide a dialplan and loopback dialstring and
>>> we'll see if we can't give you a non-loopbackish alternative.
>>>
>>> -MC
>>>
>>>
>>> On Sun, Jun 3, 2012 at 1:54 PM, Avi Marcus <avi at avimarcus.net> wrote:
>>>
>>>> ... all the normal dialplan handling. Setting CID, options, LCR stuff,
>>>> billing controls.
>>>> -Avi
>>>>
>>>>
>>>> On Sun, Jun 3, 2012 at 11:40 PM, Michael Collins <msc at freeswitch.org>wrote:
>>>>
>>>>> Let me rephrase...
>>>>>
>>>>> Since loopback is generally evil and should be avoided wherever
>>>>> possible, what does loopback give you that you can't get from doing a
>>>>> normal dialstring?
>>>>> -MC
>>>>>
>>>>>
>>>>> On Sat, Jun 2, 2012 at 11:13 AM, Avi Marcus <avi at avimarcus.net> wrote:
>>>>>
>>>>>> ... because att_xfer seems to require a "sofia/$profile/$destination"
>>>>>> directive, and he just wants the call to hit the dialplan.
>>>>>>
>>>>>> -Avi
>>>>>>
>>>>>>
>>>>>> On Fri, Jun 1, 2012 at 8:13 PM, Michael Collins <msc at freeswitch.org>wrote:
>>>>>>
>>>>>>> Why do you need to use loopback at all?
>>>>>>> -MC
>>>>>>>
>>>>>>>
>>>>>>> On Fri, Jun 1, 2012 at 3:17 AM, Alex Lake <alex at digitalmail.com>wrote:
>>>>>>>
>>>>>>>> Got a lua script for a B-party "mid-call menu". Is it legitimate to
>>>>>>>> do..
>>>>>>>> "session:execute("att_xfer", "loopback/"..destnum)"
>>>>>>>>
>>>>>>>> I've tried it and it seems to start off doing the right things, but
>>>>>>>> my
>>>>>>>> A-party gets disconnected as soon as the call to the C-Party (the
>>>>>>>> person
>>>>>>>> I'm transferring the call to) answers the call.
>>>>>>>>
>>>>>>>> Maybe better to try to orchestrate the entire affair from within
>>>>>>>> the lua
>>>>>>>> script? (Tricky for a beginner like me!)
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Alex
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>
>>>>>
>>>
>>>
>
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-- 
Best regards,

Dmitry Sytchev,
IT Engineer
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