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

Thu Sep 29 15:59:15 EDT 2016

Bringing up this old thread as I've been doing RTP-NTE to SIP-KPML on a lot
of setups but finally ran into an issue with intermittently digits not
being converted from KPML to RTP-NTE.  The debugs showed the DTMF-relay
conversion being done and the digits being sent through RTP-NTE but packet
capture shows some digits not making it onto the wire.

TAC shut it down and said this is one of the caveats and why this isn't
fully supported.

So just FYI for everyone on why it's apparently officially not supported
without a transcoder.

On Tue, Jul 19, 2016 at 4:28 PM, Justin Steinberg <jsteinberg at gmail.com>
wrote:

> interesting - i wonder why that is not supported when it works.  doc error
> or some legit technical issue ?
>
> On Tue, Jul 19, 2016 at 3:44 PM, Anthony Holloway <
> avholloway+cisco-voip at gmail.com> wrote:
>
>> I do it to, but did you know that RTP-NTE to SIP-KPML is not supported on
>> CUBE as of yet?
>>
>> http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/
>> cube/configuration/cube-book/dtmf-relay.html#concept_
>> 264617919921874995299551391601561__table_16E37E2F33CE4E0B836D2E5A809E7252
>>
>> On Mon, Jul 18, 2016 at 8:21 PM, Justin Steinberg <jsteinberg at gmail.com>
>> wrote:
>>
>>> 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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>>>
>>
>
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