Did you check the return value from wip_netInitOpts?
You use UART1 to debug the wip communications, are you sure you use the uart2 for your ppp server? If you use the uart1 to debug the wip and to test the ppp server, it will not work.
You can also try to put a delay between the stack initialisation and you bearerStart.
Good luck
Best regards,
gdt