[Freeswitch-users] Remote pickup of on-hold extensions

[sms at icefire.qza.net.au]

Hi all,

I have a scenario that I'm thinking of implementing, but not sure if it's
possible, so here's the details:

Extensions 200 to 250 are regular internal sip phones, contained in a call
group (Ext 1000)

Extensions 300 to 305 are SIP-GSM and SIP-PSTN gateways with SIP client
firmware, namely those cheap GOIP GSM units on ebay, plus an SPA3000.
These are to be configured with the logon credentials of the extension and
behave as a typical SIP client.

The dialplan will route incoming and outgoing calls via these gateways as
if they were trunks. They will restricted privileges to prevent toll
fraud. The phones will either be Yealink T28p or Grandstream GXP2124, it
depends if GS can respond with a fix for their horrible AGC or not. The
gateways will be subscribed to the phone's DSS keys as BLF's.

Now, all this so far is reasonably straight forward. The next part is the
tricky part (you might've guessed where this is going....)

Let's say a call comes in on 300, routes to the call group and is picked
up by 1000, who then puts the call on hold. The BLF key for 300 shows it
as busy/on hold. 1000 then calls 1001 to take the call. 1001 then presses
BLF 300, which causes the call to be transferred to them and automatically
answered.

So is there any way in freeswitch to replicate this behavior? I know it's
possible to do SAA, but this gets tricky if I want to have time based call
groups, or to share incoming lines between branches. The method above
allows the lines to be present on all phones, while still configuring call
groups in the usual way and more or less replicating old key system
behavior.

Cheers,
Francis