#21 Missing returns in CallToCAPI()

[tobi-wan]

In CallToCAPI(), there are obviously some missing
return values:

Quoting Ramin Nikaeen:

"
- some of the cases of the switch statement are missing
their "return" statements including cases: 5, 6, 7, 8
- maybe "return DTMF" in "case: 3 //DTMF" should be
"return err"
"

obviously true, thank you, Ramin, for pointing this one
out.