TCAP software supports only a connectionless network service. No functionality is needed from the ISP (Intermediate Service Part); only the connectionless functionality of SCCP is required. Therefore, the transaction sublayer always interfaces with SCCP through the connectionless primitives.
TCAP is intended to be used by real-time, sensitive applications (with small amounts of transferred data). The data transfer rate capability is limited by MTP2 links bandwidth. Refer to the MTP2 configuration section to learn how to configure MTP2 links to increase MTP2 links bandwidth by using multiple timeslots by link or High Speed Link (HSL) links. Each timeslot could transfer a maximum of 64KBPS. In multiple timeslots mode, it is possible to transfer a maximum of 256KBPS by MTP2 link. When using HSL, it is possible to transfer a maximum of 1984KBPS by MTP2 link. Thus the data transfer rate capability depends on the available MTP2 links and its configuration. The application real-time requirement and available MTP2 links bandwidth will mainly determine the maximum TCAP message size that could be used.
Each TCAP instance can handle a maximum of 8 userparts, 80,000 dialogs and 80,000 components. Each TCAP userpart can handle a maximum of 10,000 dialogs and 10,000 components. These limits could be modified if required by TelcoBridges upon request.
TCAP provides the functions and procedures to create dialogues between applications and invoke application operations across an SS7 network. TCAP is a service provider to MAP (Mobile Application Part) and INAP (Intelligent Network Application Protocol) and a service user of SCCP (as shown in the figure immediately below.