Re: [codec] #1: Application: 2.1. Point to point calls supporting transcoding?

James Rafferty <> Tue, 23 March 2010 23:13 UTC

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From: James Rafferty <>
To: Christian Hoene <>
Date: Tue, 23 Mar 2010 19:14:00 -0400
Thread-Topic: [codec] #1: Application: 2.1. Point to point calls supporting transcoding?
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Subject: Re: [codec] #1: Application: 2.1. Point to point calls supporting transcoding?
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Please see my comments below. 


-----Original Message-----
From: Christian Hoene [] 
Sent: Tuesday, March 23, 2010 2:53 PM
To: James Rafferty
Subject: RE: [codec] #1: Application: 2.1. Point to point calls supporting transcoding?

Hi James,

>In my view, this is dodging the real issue.  I believe there WILL be transcoding for point to point
>calls between wireline and wireless networks, where the connection is IP on both sides and multiple
>wide band codecs are used.

Could you elaborate a bit more on this scenario? Do you mean that the wireline has -for example- Skype phone with the Internet codec and the wireless end will have an LTE codec? Of course, both sides will use IP.

JR - Yes, the example of Skype from the desktop connecting to a mobile phone with wideband audio (say G.722.2) is an example.  In order for that to happen, there would likely be a border element at the network edge (what the Speermint architecture calls a Data Border Element) which negotiates the transcoding to take place in real time.  Another use case example would be where an enterprise IP phone uses a wideband codec when calling to a mobile phone, again requiring transcoding to take place to complete the call, if the two handsets do not support a common HD codec.   

>For that matter, there will also be cases where a PSTN - IP gateway is needed, but that's not usually
>defined as transcoding.

As a manufacturer of IP-to-IP gateways your insight knowledge is highly appreciated.
With best regards,

  Christian Hoene

>James Rafferty
>Product Line Director, Integrated Media Gateways
>Dialogic, Inc.
>15 Crawford Street
>Needham, MA 02494
>Tel:    781 433 9462
>Mobile: 781 929 3895
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>-----Original Message-----
>From: [] On Behalf Of codec issue tracker
>Sent: Tuesday, March 23, 2010 10:20 AM
>Subject: [codec] #1: Application: 2.1. Point to point calls supporting transcoding?
>#1: Application: 2.1.  Point to point calls supporting transcoding?
> Reporter:  hoene@…                 |       Owner:
>     Type:  enhancement             |      Status:  new
> Priority:  major                   |   Milestone:
>Component:  requirements            |     Version:
> Severity:  Active WG Document      |    Keywords:
> Question: Shall the point-to-point call support transcoding?
> If not, please add something like
> "This scenario does not include the use case of using a VoIP-PSTN gateway
> to connected to legacy telephone systems. In those cases, the gateway
> would make an audio conversion from broadband Internet voice to the frugal
> 1930’s 3.1 kHz audio bandwidth. Interconnections to the PSTN will most
> likely stick with its legacy codecs to avoid transcoding."
>Ticket URL: <>
>codec <>
>codec mailing list