I created a SIP provider (for a Grandstream GXW4108 Gateway) and noticed that when I defined a dial pattern for inbound calls I was having problems receiving the call on my pbx. Inspecting the inbound context for the provider in extensions.conf generated by Askozia shows the problem:
http://www.flickr.com/photos/41156943@N06/3789045892There is some non-printable charater (maybe a space?) between the underbar and the externsion pattern in the dialplan. The reason I included a link to a screen shot is that a copy and paste of the text seems to eliminate the problem. I was able to get the inbound calling to work find without using a dial pattern.