The Multi-Flex Trunk (MFT) provides physical layer T1 access. The capabilities of this T1 interface are determined by the host it is plugged into. High Density Voice - When you use the Multi-Flex Trunk in a high density voice network module, each DS0 can contain voice calls. The voice twork module, not the Multi-Flex Trunk, determines the T1 signalling capability (T1 CAS, ISDN PRI).