[asterisk-dev] Implementation of Broadsoft Sip Access in Asterisk to enable SLA for Sipura/Linksys

Eugene Grossi grossi at cv.med.nyu.edu
Wed Jan 2 06:30:00 CST 2008

Yes - it uses the entire SLA mechanism of Asterisk. This patch makes
Asterisk function with the Broadsoft Extensions for subscriptions and
notifications.  Each Broadsoft SIP peer is configured to be an SLA station
is Asterisk; nothing of the SLA mechanisms or meetme in Asterisk need to
 "line seize" - what does it mean for Asterisk? - really nothing.
The Broadsoft Sip Extentions assume the multiple SIP peers have access to
the same "line" and therefore need to "seize" the line if it is idle or in a
public "remote held" state. They cannot "barge" in on a call if it is in
"private held" state. Asterisk SLA is different: there are multiple unique
SIP peers who come together thru "meetme".  So when an Asterisk SIP peer
(using BroadsoftExt) requests a "line hold" it is automatically granted
since its SLA station is unique.  The Notify to the other Broadsoft SLA
peers that is generated by Asterisk SLA, is translated into a "remote hold"
state.  This lets the other handsets visually identify that the particular
SLA is active, yet it won't prevent them from dialing in and joining the
meetme SLA.  I had to enum another state "lineseize" for use in the
notification system.  When a Broadsoft SLA peer issues a subscribe with a
line seize event, the "lineseize" status is passed as the state parameter in
the notify subsystem.

It is actually less complicated than I made it sound.

Eugene A. Grossi, M.D.
Professor of Cardiothoracic Surgery
New York University School of Medicine
Suite 9-V; 530 First Avenue
New York, NY 10016
ph (212) 263-7452
fax(212) 263-5534
grossi at cv.med.nyu.edu
-----Original Message-----
From: Johansson Olle E [mailto:oej at edvina.net] 
Sent: Wednesday, January 02, 2008 4:28 AM
To: grossi at cv.med.nyu.edu; Asterisk Developers Mailing List
Subject: Re: [asterisk-dev] Implementation of Broadsoft Sip Access in
Asterisk to enable SLA for Sipura/Linksys

A few generic questions:

- Is this using the SLA implementation in Asterisk at all?

- In Asterisk, what is a "line seize" - what does it mean for Asterisk?
   (If you're not using the SLA implementation based on meetme)


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