send long sms vb6

hi all , the application work as bridge, the user send sms to application which is connect to modem .. the modem will send the user request to server the server will replay by sms to application and then the application send back the request information to user, what has been done , 1- interface in vb6 to connect to modem .. 2- it receive the sms from user and redirect it to server (it work fine) the problem now the server replay with sms to application in hex which divided into 3 parts it may go to 4 parts now i should send the 3 parts to user as one sms , i think by using PDU, the freelancer who accept this, i will send him the application that been done vb6 , the only part he should do is PDU part to be sent to the user. regards