[VoiceOps] Cisco 7940 PTT

[John Todd]

The 79xx phones don't support it.

But... theoretically, you could do something LIKE a push-to-talk.   
They support auto-answer, and they also support PLAR (private line  
auto ringdown, aka hotline, where the moment you pick up the phone it  
dials a pre-defined extension.)

It would be a 1-to-1 push-to-talk, and it wouldn't exactly be push-to- 
talk, but in theory... (note: theory often differs from reality in  
practice.)

There's also the telnet administration interface on some (all?)  
versions of the SIP software load, which if enabled (and you have the  
password) makes it possible to send out-of-band commands the phone to  
press any button combination, which is a really ugly hackable interface.

The real answer would be to get phones from a company with a  
development effort that is concerned about SIP.  The 79xx series  
traditionally has not cared about SIP, and has focused on CCM in all  
of it's proprietary nonsense.  Linksys/Sipura did a far better job  
doing the "right thing" with SIP than traditional Cisco ever did on  
the desktop, and that rift still shows today despite being (now) the  
same company.

JT


On Nov 15, 2009, at 8:43 PM, Scott Berkman wrote:

> The "original" Cisco phones (7940, 7960, 7905, 1912) that have  
> official SIP
> support have never had any advanced features (namely subscribe,  
> presence,
> answer-after, etc) to the public SIP firmware.  Some of these  
> features are
> supported with varyingly proprietary SIP functions on the CCM SIP  
> versions
> of the Firmware.  Using these with other platforms is possible, but is
> neither supported or documented in any official capacity.  You can  
> find some
> basic instructions out there if you feel like wasting a lot of time  
> on the
> project, but I'm not sure that all of the functions have ever really  
> been
> figured out from a provisioning standpoint.
>
> That being said, PTT is possible on any phone with the right feature
> platform in some manner.  For instance, BroadSoft implements PTT  
> outgoing
> using a star code, which could be auto answered by a different phone  
> that
> does have support for the answer-after tag.  A PTT call to one of  
> these
> devices would just ring in like any other call however.
>
> The Cisco/Linksys/Sipura SPA series of phones has a similar design  
> and a
> much more full list of supported features.  There is also a new line  
> of
> Cisco multi-media phones (9X00) that may or may not have this type of
> support, but does advertise SIP interoperability with "partner"  
> platforms.
> I don't know much about them beyond that.
>
> 	-Scott
>
> -----Original Message-----
> From: voiceops-bounces at voiceops.org [mailto:voiceops-bounces at voiceops.org 
> ]
> On Behalf Of Alex Balashov
> Sent: Thursday, November 12, 2009 9:51 PM
> To: Ujjval Karihaloo
> Cc: voiceops at voiceops.org
> Subject: Re: [VoiceOps] Cisco 7940 PTT
>
> No.
>
> --
> Sent from mobile device
>
> On Nov 12, 2009, at 9:30 PM, Ujjval Karihaloo
> <ujjval at simplesignal.com> wrote:
>
>> Can a Cisco 7940/7960 do Push to Talk..any config suggestions?
>>
>>
>>
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