pppd hangs up about ppp

[Hi-Angel]

If someone knows a way to compile a debug version -- please, tell me. Right now the make install installes a stripped version. Fortunately I found the not stripped one in the ./pppd directory. Here is a backtrace

(gdb) bt
#0  0x00007ffff74be4b0 in __open_nocancel () at ../sysdeps/unix/syscall-template.S:81
#1  0x000000000042790b in open (__oflag=2, __path=<optimized out>) at /usr/include/x86_64-linux-gnu/bits/fcntl2.h:53
#2  connect_tty () at tty.c:726
#3  0x000000000041990c in start_link (unit=unit@entry=0) at auth.c:560
#4  0x00000000004095e6 in main (argc=4, argv=0x7fffffffe648) at main.c:539

[Hi-Angel]

I am found in a code a comment that in this open() the pppd awaits for some Data Carrier signal, such a signal should give a turned on modem. After googling around I found a way to disable this: it is the local. So call should have looked like pppd local -detach 10.5.57.198: /dev/ttyS4. It is esentially for me as I am need to receive and send data through a Unix socket, not the real serial port.
Solved.