Can't access VOIPo voicemail

[tritch]

Yes. I believe you are in the correct area to modify your dial plan. I don’t have an Obi ATA myself, but use a Linksys SPA2102 which closely matches the same dial plan rules.
Try adding the rule 123S0| at the start of the dial plan or |123S0 at the end of the dial plan. Don’t forget to add the vertical bar |

Examples:
(123S0|1xxxxxxxxxx|<1>[2-9]xxxxxxxxx|011xx.|xx.)
or
(1xxxxxxxxxx|<1>[2-9]xxxxxxxxx|011xx.|xx.|123S0)

If you have any issues or need help, you may want to check out this thread:
http://www.obitalk.com/forum/index.php?topic=34.0

Just a word of caution....there are 3 valid area codes in the US that start with 23X (231 in Michigan, 234 in Ohio, 239 in Florida). So, if you happen to attempt to dial one of these 3 area codes by dialing 1-23X-XXX-XXXX, you will go straight to your voicemail instead of reaching that number. BTW, I use 10 digit dialing for all my needs instead of 11 digits, so this issue is not valid for me. Voipo accepts 10 digit dialing just fine.