Change the timer settings is BOTH COS of the Trunks AND handsets
Call Fwd No Ans Timer: 15
No Ans Recall Timer: 17
4 Rings, then forwards
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Call Fwd No Ans Timer: 17
No Ans Recall Timer: 19
5 Rings, then forwards
Hope this helps... and no you do not need to reboot the system for settings to take in effect. If you change settings they happen in a sec after you save. If you test out your changes and they don't work, then its something else.