Create SMS gateway software and connect into modem gsm and can connect with multiple computer

i wanna make software that can manage sms from my modem gsm, that software can connect into any computer which is connect by lan and will sync with all of that computer everytime. that software have an admin account and another account is employee account. the sms design is like chating, so when we view an number then all history of that number will be shown and the message sort by time one by one. beside that when we reply a message then in that message will be recorded replied by which id name. we can search sms by number and search by text inside the sms, we can send sms to many list number too we can set maximum outgoig message per hour too. all sms can be delete but only admin account have that permission, i have attach picture for detail design and for further explaination