[cisco-voip] DTMF interworking on CUBE - asymmetric payloads

[Justin Steinberg]

yes, CUBE can do RFC2833/NTP to a Telco and SIP-KPML to CUCM.   I do this
for calls that terminate on CCX IVR since CCX does not support RFC2833.
With only rtp-nte on the dialpeer from CUBE to CUCM, CUCM will invoke a
MTP.   Adding sip-kpml to the dial-peer will allow RTP directly from CUBE
to CCX without any MTP in the middle.

On Mon, Jul 18, 2016 at 5:08 PM, Ed Leatherman <ealeatherman at gmail.com>
wrote:

> Thanks Daniel, that helps a lot in understanding the feature. I'm curious
> if CUBE will also translate digits to KPML in this case if the leg to CUCM
> has that negotiated. Wish I had a lab built out for this :)
>
>
>
> On Mon, Jul 18, 2016 at 4:22 PM, Daniel Pagan <dpagan at fidelus.com> wrote:
>
>> Ed:
>>
>>
>>
>> I specifically worked with the dynamic payload option for a few cases
>> that came my way. Based on my findings, when a dynamic payload type (such
>> as 100/101/etc.) is received by CUBE, it will check if the next-hop
>> dial-peer has the asymmetric payload feature enabled and, if it is, will
>> pass the received payload type through to the next call-leg. Take a look at
>> my screen shot below. This was taken from some old notes where AT&T was the
>> customer’s carrier.
>>
>>
>>
>>
>>
>> The call flow above shows two call-legs, and *the arrows represent an
>> offer/answer exchange*.
>>
>>
>>
>> With asymmetric payload enabled on both call legs, the 100 offer from ATT
>> is passed to CUCM despite 101 being the default PT for NTE. In the SDP
>> answer from CUCM, we’re getting PT 101 -- since asymmetry is enabled on the
>> DP to ATT in this call flow, we pass the 101 through to ATT despite having
>> received PT 100.
>>
>>
>>
>> This results in asymmetry on our negotiated PT for each call-leg.
>>
>>
>>
>> *Let’s change it up a bit… A second example.*
>>
>> If asymmetry was disabled on the dial-peer to CUCM but enabled to ATT, we
>> would receive 100 PT from ATT, send 101 to CUCM, receive 101 from CUCM, and
>> send 101 to ATT. The resulting PTs would be symmetrical between CUBE and
>> CUCM, but asymmetrical between CUBE and ATT.
>>
>>
>>
>> See screenshot below for a third example:
>>
>>
>>
>>
>>
>> This example shows asymmetric payload disabled on both call-legs using
>> the same call flow. CUBE receives PT of 100 from ATT -- the outbound
>> dialpeer has asymmetry disabled, so it transmits the PT specified for that
>> dial-peer (default 101 or any hardcoded dynamic PT) to CUCM. We then
>> receive 101 from CUCM and, since our inbound dial-peer has asymmetry
>> disabled, CUBE sends 100 to match the original PT it received. Asymmetry is
>> disabled so CUBE is not passing the received dynamic PT through to the
>> next-hop dial-peer - we have symmetry on both call legs for our NTE PT.
>>
>>
>>
>> Note that CUBE has no issues receiving one dynamic PT for NTE and sending
>> another (ex: receiving PT 100 and transmitting 101 for RTP-NTE) on the same
>> call leg.
>>
>>
>>
>> Hope this helps
>>
>>
>>
>> - Dan
>>
>> --------end attach---------
>>
>>
>>
>> *From:* cisco-voip [mailto:cisco-voip-bounces at puck.nether.net] *On
>> Behalf Of *Ed Leatherman
>> *Sent:* Monday, July 18, 2016 3:10 PM
>> *To:* Cisco VOIP <cisco-voip at puck.nether.net>
>> *Subject:* [cisco-voip] DTMF interworking on CUBE - asymmetric payloads
>>
>>
>>
>> I'm trying to get my head wrapped around some DTMF interworking
>>  features...
>>
>>
>>
>> I have this setup:
>>
>>
>>
>> UCM ------ CUBE ------- 3rd party system
>>
>>
>>
>> For both call legs through CUBE I'm advertising kpml and rtp-nte for
>> dtmf-relay
>>
>>
>>
>> The 3rd party sometimes sends me rtp payload type 101 for nte's, and no
>> kpml, and things work (as a bonus I observed CUBE correctly interworking
>> the nte's from the pbx into KPML, so uccx didn't break).
>>
>> Sometimes they send type 98 and no kpml, and things don't work.
>>
>>
>>
>> I'm trying to understand what is happening and what feature should fix it
>> (without breaking other things)
>>
>>
>>
>> Assumption:
>>
>> "dtmf-relay rtp-nte kpml" is telling CUBE to offer/accept rtp type 101
>> only for nte. I observe that CUBE negotiates KPML only for the associated
>> call leg back to UCM and doesn't bother with rtp-nte, so its just like any
>> other codec that CUBE doesn't care about.
>>
>>
>>
>> So.. if third party system ONLY sent me dtmf-relay with payload type 98,
>> could I just set the rtp payload type for this to 98 on the inbound dial
>> peer? would CUBE then correctly switch these up to 101 headed back to UCM?
>>
>>
>>
>> How can I (or can I at all) make this work in my particular case were I
>> could receive both?
>>
>> I see "asymmetric payload dtmf" thrown about as a possible solution, but
>> I'm having trouble understanding what it actually does. It sounds like it
>> passes these payload types through CUBE, so UCM could be getting rtp
>> payload type 98 - it knows what to do with it? It seems like then CUBE
>> wouldn't be able to translate things to KPML this way...
>>
>>
>>
>> I'm reading
>> http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/cube/configuration/cube-book/voi-dymc-payld-dtmf.html
>> but I guess I'm just not drinking enough coffee today (or too much) and I'm
>> not getting what exactly this command does.
>>
>>
>>
>> Anyone know how that asymmeteric command works?
>>
>>
>>
>> --
>>
>> Ed Leatherman
>>
>
>
>
> --
> Ed Leatherman
>
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>
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