SP143 is designed for analog card AE1610E/P. It's to split RJ45 jack to RJ11 jack that is used to connect the telephone line.
SP142 is designed for analog card A2410P/AE2410P. It's to split RJ45 jack to RJ11 jack that is used to connect the telephone line or telephone.
SP140 is designed for analog card A1200P. It's to split RJ45 jack to RJ11 jack that is used to connect the telephone line.