I set up a mobile extension to my cellphone.
When I dial the mobile extension pilot(169), after 7-9 seconds my cell phone rings.
But it takes so long to reach the mobile, and the extension dials out gives a “du du” tone in this period, it gives out normal ring tone when cell phone open the key board.

PCPro mobile extension list: port 169
11-02 extension number =169
15-01-01name= my mobile
15-22-01SPD target =1999
13-04 SPD 1999: number =04xxxxxxxx, name =xxx
21-13 ext169: calling party number =04xxxxxxxx

any idea about the strange tone and long waiting time?