Main portion of the advantages of the Asterisk server appears from it being an open source downloadable product. Most of the users, especially business people, can find it difficult to understand the idea behind this principle, or free software, but a business models behind open source are different and specific, as in case with Asterisk server.
COMTALK delivers DID/DDI numbers & termination in Denmark (but also most of the world) We offer SIP and are also MVNO, which means low cost calls to the Danish Celluar networks