The Quintum D3000 doesnt take 2 T1s, it takes one E1 which is the T1 equivalent used in Europe, a T1 is used in North America. A T1 handles 24 voice channels while an E1 handles 30 voice channels. The D2400 takes a T1, you can only only plug 1 PSTN (telephone)Line whether T1 or E1 into a D2400 or D3000