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Three-way calling, SPA112

David30
Level 1
Level 1

What is the architected method of initiating a three-way conference call with the SPA112 (i.e. with local mixing)?

Some Cisco ATAs appear to use double-flash.  The SPA112 has a "conference activation code" parameter which is blank by default, suggesting it's optional or an alternative since it would have an assigned value otherwise.

However I've found it works once the 'flash' key is operational: press flash, key in the conference activation code, dial the third party and talk to them, then press flash again and the call is set up.

  • Is this the best, or only, way of establishing a three-way call?
  • Why is there no assigned code?
  • Does a code need to be in the form *-digit-digit and, if not, what constraints are there?

Finding a code which doesn't conflict with an assigned code is a job; I put all the codes in a spreadsheet and sorted them in order to find a free one (*33).  Double-flash would be nice, but I couldn't see any evidence of it in the Admin Guide.

DL

 

 

 

1 Accepted Solution

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Thanks, Dan.  The (first number, flash,second number, flash) sequence was the sort of thing I was looking for but I haven't tried it yet.  However the other method I mentioned (assign a star-code for ActConfCall and key it before dialling the second number) works well!  Calls are very clear.


@Dan Lukes wrote:

True. But even it require support from upstream. If it will not deliver second call to same number, just because it's considered busy, you can do nothing with it.


Yes, I'd already checked that with my ISP.

DL

 

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4 Replies 4

Dan Lukes
VIP Alumni
VIP Alumni

None. SPA112 is just bundle of two ATAs. Features like 3-WAY calling needs to be implemented on upstream call control device (a.k.a. PBX or voice/SIP proxy). SPA112 supports various methods to activate a feature, but exact method depends on call control device requirements.

It seems you discovered one method. No one but someone familiar with upstream proxy configuration knows there's other method possible. Ask the PBX administrator for help.

 

And no one but you know which method (from list of possible methods) is best for you. It's matter of personal preference.

The Admin Guide states that an SPA1x2 can locally support a maximum of four concurrent calls, presumably involving four SIP / RTP sessions (i.e. two per FXS port).  My understanding is that switching back and forth between calls with the 'flash' button and mixing of the audio streams during a three-way call is all done locally in the device, and 'flash' events are not forwarded downstream like DTMF signalling.

 

True. But even it require support from upstream. If it will not deliver second call to same number, just because it's considered busy, you can do nothing with it.

 

You can use "Call Number Press FLASH , Call 2nd Number , Press FLASH" sequence to initiate 3 way call. As long as you will follow restrictions (e.g. both calls are using same uncompressed codec) it may work, unless your upstream proxy will not allow two active calls at the same time.

 

It seems I misunderstood your question. I has assumed you tried documented way and it doesn't work for you. 

Thanks, Dan.  The (first number, flash,second number, flash) sequence was the sort of thing I was looking for but I haven't tried it yet.  However the other method I mentioned (assign a star-code for ActConfCall and key it before dialling the second number) works well!  Calls are very clear.


@Dan Lukes wrote:

True. But even it require support from upstream. If it will not deliver second call to same number, just because it's considered busy, you can do nothing with it.


Yes, I'd already checked that with my ISP.

DL

 

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