Hi Barry,
Does your running config show outbound POTS dial-peers? If it does check the preference, it may be at it's default of 0 which is the highest preference. Note: When you set the preference order, the lower the preference number, the higher the priority. The highest priority is given to the dial peer with preference order 0 and it is the default value. You can have a preference value between 0 to 10.
You can also run the command "Show dialplan number 9911", to find matching dial-peers (used 9911 as an example you can test with any 10 or 7 digit number). The output can be very verbose so you may want to use the "| include tag" filter at the end. I pasted an example below.
show dialplan number 916473735634 | i tag
tag = 1020, destination-pattern = `91[2-9]..[2-9]......',
voice reg type = 0, corresponding tag = 0,
voice class perm tag = `'