If your inbound calls are working, then you have the
PSTN to VoiP dialplan set correctly. In this case it is used to direct a call coming from a PSTN line
to 3CX. For outbound to work, you have to do more than name an outbound rule...you must specify what digits (prefix/length) it applies to, and if any are to be stripped before being sent to the gateway. the
VoIP to PSTN Dialplan is not
normally used when the 3102 is a 3CX trunk as you would do all of your digit manipulation in 3CX and use one stage dialling.
https://www.3cx.com/blog/voip-howto/outbound-rules-a-complete-example/