I'm living in Montreal. We have two area code 514 and 438.
When I call 438-xxx-xxxx number through auto attendant (option 2), my obi200 will reboot. But calling 1-438-xxx-xxxx number won't have this issue. Also, calling other number, such as 514-xxx-xxxx, won't have this issue. Direct call (from phone port) to 438 number won't have this issue either. So far, only calling 438-xxx-xxxx number through auto attendant (option 2) will cause ATA reboot. There is a test number 438-580-4001 (Telus voicemail) you can try to reproduce this issue.
This is a bit frustrate since I don't want to dial extra 1 before area code.