This option begins move the towards integrated messaging. An integrated message in-tray simply extends the scope to cover voice and fax messages. The in-tray contents can be built up from voice and fax message waiting indications sent across the LAN from the voice processing system. When a voice message is opened it must be delivered to the telephone, so a command must pass across the LAN to the voice messaging system. This command causes the voice message to be delivered to the correct telephone.
Some implementations allow for either delivery mechanism to be used.
The CTI approaches described as first party and third party are call control rather than media control mechanisms. These approaches cover functions that deal with the making, transferring and clearing of calls. CTI of this sort does not concern itself with the content of the calls. The computer may be mediating voice, data or even video calls, it makes little difference in so far as call control is concerned. Media control is more concerned with moving calls and messages between different media resources.