[ATLSIP] Call transfer and hold

[Ilian J. C. P. <ip...@so...>]

Hi.

I now have a rough implementation for call hold and call transfer 
(attended/unattended). The thing works but the implementation leaves a 
lot to be desired. I will try to iron out the kinks first before 
applying the changes to CVS. Expect this within this week or next week 
at the latest.

- Ilian