Managing third party call control services with call processing language

An extension of the third party call control mechanism to call processing language is presented. CPL is based on the extensible markup language (XML). It is proposed to implement some basic services used in Internet telephony. The aim is to let the end-users of the telephony architecture develop their own customized services, e.g. call forwarding to voicemail (on busy & no answer), incoming and outgoing call screening and e-mail notifications of the call set-up events to the subscriber.