Incoming line identity and ALS

[Chris Pitchford]

Hi all,

I've been looking through the 0.8 source code for some indication of ALS 
support.

ALS (or line-2) allow two different numbers to be attached to a mobile 
device. The device can accept calls from both numbers and make calls from 
either of the two numbers, effectively acting as if two lines were 
attached to the device.

http://en.wikipedia.org/wiki/Alternate_line_service

AT+CNUM reports all of the lines available on a mobile device that 
supports/is using ALS.

I guess there are two problems for supporting ALS in ofono.

First is selecting which line/number to use when making a call. I'm not 
certain how handsets make this distinction and I wonder if it might be 
vendor specific.. Changing out bound line seems to be set as a mode rather 
than on a
per-call basis. Switching out bound lines is sometimes locked with PIN1.

The other problem is identifying which line was called by a remote caller. 
I believe +CDIP includes this information (after each RING / +CRING)