dCAP is the international standard for Asterisk consultants. A Digium Certified Asterisk Professional has demonstrated advanced knowledge of many different telecommunications subjects, both general and specifically related to Asterisk by sitting an examination including both practical and theoretical components. Training and testing subjects for dCAP include telephone line technologies (BRI, PRI (E1/T1), PSTN / POTS), VoIP signalling standards (IAX, SIP, h.323, MGCP), codecs and translation of media (g.729, uLaw/aLaw, g.722, g.723.1 etc), call routing commands and modules and functions specific to Asterisk.