Connect VOIP phone To LAnd line phone and then make call through lan line

Hello,
I want to know if it is possible to have the following:

I’m using VOIP soft phone from side “A” and make call to Side “B” which is another soft VOIP phone,

PC on side “B” has built_In modem with land phone line connected to it, is it possible to connect B’s VOIP phone to its land line and dial number from Side “A”(normal land phone number)then connect them all,

Is there any way to do that or any software can help me to do that,