Unable to Switch Call

[UmairShahzad]

Can anyone help me when i try to do conference call my s21 plus is giving error or unabke to switch call while one person is already on call and second i can't make. Screenshot is attached. I will apriciate if anyone help me to fix this issue 

[innovativeAR121]

Bro turn on in setting call forwarding or dual call and notify me when another call me

[FahadAyaz]

Bro mere saath bhi Yahi masla Tha lekin bad Mein Pata Chala Ki yah network ki vajah se hai Agar aapke pass jazz ka network Hai To iska Ek code Hai conference call ka vah dial Karenge to tab aapki conference call Hogi aapke pass jo bhi network hai Google per search kar len code aapko mil jaega

[user9992112]

Ap ko network ke helpline par call kar k conference call service active karwani parregi