solve the problem of outgoing calls

To solve the problem of outgoing calls taking 10 seconds to start ringing, fix your dial plan. (Line tab in admin/advanced.) This, along with many other default settings in Linksys devices, are not practical for North America. Here's a generic dial plan that should work properly for 10-digit dialing:

( [23456789]11 | *xxx. | <:1>[2-9]xx[2-9]xxxxxxS0 | 1[2-9]xx[2-9]xxxxxxS0 | 011xxxxxxx. | [#*x][*x][*x][*x][*x][*x][*x][*x][*x][*x][*x][*x]. )

With regards to the next call always appearing busy, it sounds as if TekSavvy's equipment is not properly responding to SIP NOTIFY messages. You can work around this issue by setting the NAT Keep Alive Msg (Line tab in admin/advanced) to simply KeepAlive.