A few quick suggestions to start this off: See if your provider is listed here: Howto: Setting up VOIP Provider Trunks Note that the pages in that section were contributed by many people and some may be more accurate than others (I'm particularly suspicious that the one about Broadvoice isn't right, for example). Make sure that there is a context=from-trunk line in your trunk settings. Often they tell you that this goes in the USER details, but many providers treat you as an extension, not a peer, and in that case the USER context and details are totally ignored! So, if you can't get incoming calls to work, try moving the context=from-trunk to the PEER details and see if that makes any difference (if it does, you should probably clean out the USER context and details). And, make sure you have created an incoming route and that the DID matches the number that follows the forward slash in your trunk registration. In other words, your registration string should take the form firstname.lastname@example.org/yourDIDnumber, and whatever you have in the yourDIDnumber position is the DID you should be using for your inbound route. If that doesn't help, see How to get the DID of a SIP trunk when the provider doesn't send it (and why some incoming SIP calls fail) (the stinking smiley is hiding a colon and a lowercase "p" - please, someone, for the love of God, configure this forum software properly, or put it out of its misery!).