The affected call types for +CHUP were set to only ACTIVE calls.
Instead the affected set should include INCOMING, DIALING, ALERTING and
ACTIVE calls.
Thanks to Ionut Dediu for the diagnosing and reporting this issue.
Some phones do not send the corresponding call state update (+CIEV)
after a successful release-and-swap operation (AT+CHLD=1).
This has been observed with a Nokia 500, while testing ReleaseAndSwap()
while an active and a held call exist:
ofonod[20414]: > AT+CLCC\r
ofonod[20414]: < \r\n+CLCC: 1,0,1,0,0,"<number1>",145\r\n
ofonod[20414]: < \r\n+CLCC: 2,0,0,0,0,"<number2>",145\r\n
ofonod[20414]: < \r\nOK\r\n
ofonod[20414]: > AT+CHLD=1\r
ofonod[20414]: < \r\nOK\r\n
After this, no +CIEV is received, but the call has been hung up.
The proposed approach to solve this consists of using AT+CLCC, unless
a call release has been received within a specific time period.
The result fixes the problem as can be seen below:
ofonod[20847]: < \r\n+CLCC: 1,0,1,0,0,"<number1>",145\r\n
ofonod[20847]: < \r\n+CLCC: 2,0,0,0,0,"<number2>",145\r\n
ofonod[20847]: < \r\nOK\r\n
ofonod[20847]: > AT+CHLD=1\r
ofonod[20847]: < \r\nOK\r\n
ofonod[20847]: > AT+CLCC\r
ofonod[20847]: < \r\n+CLCC: 1,0,0,0,0,"<number1>",145\r\n
ofonod[20847]: < \r\nOK\r\n
ofonod[20847]: < \r\n+CIEV: 5,2\r\n
ofonod[20847]: < \r\n+CIEV: 5,0\r\n
While processing the result of AT+CLCC, process the differences in a way
that disconnections are reported first, then call state changes and
finally new calls.
The goal is to avoid unnecessary transitional states such as two active
calls existing at the same time.
A call that moves from the dialing to active state before the +CLCC response
will not properly be added as a voicecall. This is because the dialing callback
was using simplified handling and only looked for calls in the dialing or
alerting state.
AT sequence that exhibited the failure (AG device was an iPhone accessing
visual voicemail):
> +CIND: ("service",(0-1)),("call",(0-1)),("callsetup",(0-3)),
("battchg",(0-5)),("signal",(0-5)),("roam",(0-1)),("callheld",(0-2))
...
> +CIEV: 3,2
< AT+CLCC
> +CIEV: 2,1
> +CIEV: 3,0
> +CLCC: 1,0,0,0,0,"**21153**",129,"Voicemail"
Callheld move from 1 (active and held calls) to 2 (all calls on hold) may
result of:
- active call has been dropped by remote,
- an intermediate state during a call swap which will be followed by a
move back to 1.
So, wait a little before checking calls state.
This patch was generated by the following semantic patch
(http://coccinelle.lip6.fr/)
// <smpl>
@fix disable is_null,isnt_null1@
expression *E;
@@
- !E
+ E == NULL
// </smpl>
If we are in multiparty call, remote AG won't update indicator
if any call in multiparty call is released by CHLD=1x. So we
have to poll it periodically.
Denis Kenzior
Mikel Astiz
Michael Brudevold
Marcel Holtmann
Frédéric Dalleau
Frédéric Danis
Jeevaka Badrappan
Lucas De Marchi
Helen Clemson
Sjur Brændeland
Zhenhua Zhang