I made it!
It takes me about 15 hours 
port config for BL2500 CTS RTS :
#define USE_PPP_SERIAL 0x10 // bring in PPP and use serial port B
//#define ETH_MTU 1500
#define ETH_MAXBUFS 3
#define SERE_CTS_PORT PGDR
#define SERE_CTS_BIT 3 // use PC3 as CTS (input)
#define SERE_RTS_PORT PGDR
#define SERE_RTS_SHADOW PGDRShadow
#define SERE_RTS_BIT 2 // use PC2 as RTS (output)
#define MODEM_SERE_ENABLED // Serial Port to Connect Modem to
#define MODEM_SERE_HANDSHAKING // Enables Handshaking (RTS/CTS)
#define MAX_MODEMS 1 // Number Of Modems to Use (6 max)
#define MDM_WAVECOM 0 // Used in sample only
#define EINBUFSIZE 255 // Largest RX Packet Avail.
#define EOUTBUFSIZE 255 // Largest TX Packet
#define MDM_INBUFSIZE EINBUFSIZE // Modem Input Buffer Size
#define MDM_OUTBUFSIZE EOUTBUFSIZE // Modem Output Buffer Size
and for modem
Modem_Serial_Options(MDM_WAVECOM, M_SERE, baudrate, PARAM_8BIT, PARAM_NOPARITY, 1);
Modem_Signal_Config(MDM_WAVECOM, MODEM_RTS, Modem_WrPortI, PGDR, &PCDRShadow, SERE_RTS_BIT, 0);
Modem_Signal_Config(MDM_WAVECOM, MODEM_CTS, Modem_RdPortI, PGDR, &PCDRShadow, SERE_CTS_BIT, 0);
Modem_Port_Open(MDM_WAVECOM);
#if (_CPU_ID_ < R3000)
serMode(1);
#endif

but I have problems with PPP connection
I get some garbage from modem…
ifconfig(iface[count].ifx,
IFS_PPP_INIT,
IFS_PPP_SPEED, 9600L,
IFS_PPP_FLOWCONTROL, 1, // 1= use flowcontrol
IFS_PPP_RTSPIN, PGDR, &PGDRShadow, 2,
IFS_PPP_CTSPIN, PGDR, 3,
IFS_PPP_SENDEXPECT, DIALUP_SENDEXPECT,
IFS_PPP_REMOTEAUTH, DIALUP_NAME, DIALUP_PASSWORD,
IFS_PPP_HANGUP, "ATH",
IFS_PPP_MODEMESCAPE, 1,
IFS_PPP_ACCEPTIP, 1,
IFS_PPP_ACCEPTDNS, 1,
IFS_UP,
IFS_END);
waitfor(!(ifpending(iface[count].ifx) % 2));
Any suggestion?
My head boiling… and I am going to sleep…
soo long people …