gsmd doesn't provide a way to know when an incoming call has hung up before being accepted

[mickey@…]

To reproduce:

Call your Neo until it rings. Hang up on the calling station. Neo Dialer does
not recognize it.

[balrogg@…]

I once looked into this a couple of weeks ago and I didn't find any way to
enable any kind of notification from modem when the peer hangs up, but very
likely I haven't been looking close enough (perhaps +CPI:.. ?). Instead I added
a timer that fires when there's no +CRING for two seconds and notfies gsmd
clients. The commit id was aba18c571f07e8467dac488a3ca0697002628d9c in the gsmd
tree at ​http://folks.o-hand.com/andrew/gsmd.git, it also fixes a couple of other
issues.

[thomas@…]

Tick, perhaps you could comment on whether you think the time out should be
implemented on the gsmd side or the client side?

[tick@…]

The version of aba18c571f07e8467dac488a3ca0697002628d9c on
​http://folks.o-hand.com/andrew/gsmd.git
is dealing with RING timeout but not +CRING timeout.

This patch is committed as R3572.

It works for gsmd with AT+CRC=0 && without AT%CPI=2 or 3
Currently gsmd use the %CPI information to tell if a call is disconnected.

A timeout scheme of +CRING is still needed if another modem, without %CPI
support, is used.

[chris@…]

Dialer bug re-filed in 1153 with patch attached, changing this bug to represent
the underlying issue which has long since been fixed.