PPPExample -Echo client to a remote access server via a modem

PPPCheckLink failure

I am using Digi ConnectEM board to set up a ppp client session and to get connected to an ISP. My modem is connected in com port 1(/com/0) and i am using the same example code with the appropriate changes in ppp_test.h and appconf.h. The source code which i am using is attached here.

The modem is dialing and getting connected to the server. But the PPPCheckLink is always giving error code 3( PPP_NOT_UP). Hence i am not able to get the server Assigned ip address of the pppinterface. Is there any other settings needed for the proper working of ppp or is there any alternate method?