Dial plan/call routing issues

Running 1.817.210.58-1 on a Comcast PRI. Having an issue when we dial Rondee conference calling services at 916-209-4534, the calls end up at the IVR greeting. We’re using SPA504G phones with the default end point config. Here is the dial plan:

( [23456789]11 | *xxx. | <:1352>[2-9]xxxxxx | <:1>[2-9]xx[2-9]xxxxxxS0 | 1[2-9]xx[2-9]xxxxxxS0 | 011xxxxxxx. | [#*x][*x][*x]. )

I’m still getting comfortable reading these, so any input would be appreciated.

They also can’t dial the ‘local’ area code 971 without first dialing a 1.

A pointer to a primer on interpreting and creating dial plans would be great, too.