1) TEA1062 is just a speech circuit. You can transmit and receive only voice signals from telephone line. It does not provide DTMF generation and DTMF detection.
2) The page you referred to, is for TP5088 from National. The only major disadvantage with transformer is cost.
3) If you use TP5088, it willnot decode DTMF. YOu will need some other chip for this purpose.

4) Why don't you go for MT8880 wich has DTMF generation, DTMF detection, Call progress detection ???

IA