If you tried to forward your number to a SIP account (e.g. SIP/ This e-mail address is being protected from spambots. You need JavaScript enabled to view it .3), and the DID is still not working, please check if you have added all DIDWW IP addresses.
More information for SIP you can find in How to Set SIP Configuration for DIDWW DID Number on Asterisk?
To find the updated list of the IP addresses The List of DIDWW IP Addresses
Article is in the following categories:
KB » Troubleshooting» SIP
KB » Troubleshooting» SIP

I Cannot Map My Number to SIP Account