set sm-RP-OA in gsm411_sms.c

Hello, I need to set originating address in MO SMS (SM-RP-OA)... I found this field in src/host/layer23/src/mobile/gsm411_sms.c --> /* no orig Address */ data = (uint8_t *)msgb_put(msg, 1); data[0] = 0x00; /* originator length == 0 */ Field has 0 length. Can anybody pleas help me how to set this field to some MSISDN...I know that there must be some fields for TON,NPI, number ... but I don't know how to write these fields into source code... With this change i want to find out how MSC behave when is field SM-RP-OA set to some real MSISDN. Thank you! Andrew