[Standards] Jingle PSTN sessions

Stephen Paul Weber singpolyma at singpolyma.net
Sun Jan 22 19:07:09 UTC 2017

> Did you see https://tools.ietf.org/html/draft-ietf-stox-media-07 which 
> describes Jingle<->PSTN gateways (assuming the latter speaks SIP)?

I had seen related RFCs, but that's a good resource for SIP bridging, which 
I expect we may do some of further along in the project.

>> My main use case is a PSTN Gateway which could, on receiving an inbound 
>> call, be told by the XMPP client to forward the call over PSTN to a 
>> receiving number (either with upstream caller id or rewriting caller id, 
>> depending on application).
> That sounds more like you want a call-control protocol.
> https://xmpp.org/extensions/xep-0327.html

That looks a lot more like Twilio's control language than what I'm looking 
for (since I'm first party, and it's for "third party").  Though it *almost* 
has the particular case I described as 
https://xmpp.org/extensions/xep-0327.html#def-redirect it is basically 
focused on phone-tree style use cases and not on establishing 
person-to-person phone calls (in fact, "redirect" is AFAICT the *only* way 
Rayo allows for establishing person-to-person calls, unless I'm missing 
something).  There's also a lot of weirdness in the protocol (like JIDs for 
calls? and resources for in-progress call commands?? each with presence???)  
though I could probably just hold my nose on that kind of thing if needed :)

It would be nice if negotiation could happen to choose Jingle-RTP where 
supported, or PSTN where supported (on some priority when both are 
supported).  I suppose in my mind (and in my original example) I also had 
cases where an "inbound call" in actually completed by the "recipient" 
initiating over PSTN, but that is probably less necessary in any near-term 
use case.

I suppose Rayo-redirect is generic enough that the recipient could 
"redirect" to their own XMPP address to request Jingle-RTP negotiation be 
started?  And redirect through a service that needs extra DTMF could be a 
redirect to "tel:+15558881234;ext=*714" (though RFC3966 does not allow */# 
in "ext" :P).

That leaves call-redirection with callerid rewriting.  Ah, here found 
another way to do person-to-person: <dial/> with a <join/> child.  Seems 
like you could always do <redirect/> in this way instead, it's a bit more 
complex but gives more control?

So, I suppose if I implemented parts of Rayo in the right ways I could make 
it suit my immediate needs at least.  Doesn't solve the more general use 
case of two XMPP users calling each other over PSTN, but that's not an 
immediate need.

Who is implementing Rayo now?  And for what purposes?  I'm curious what use 
cases it's actually imagined for (might give context to my imagined abuses 
:) ).

Stephen Paul Weber, @singpolyma
See <http://singpolyma.net> for how I prefer to be contacted
edition right joseph

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