Cellular Conference Not working in 8.1.1

[amitabhbansal]

friends
in all my iphone's with ios 8.1.1 i am unable to make cellular conference call, while in first call when i try to add a call or dial a number it does but the dialer screen goes back and not able to merge the call
is there anything i can do to make it cure?

 

[The Doctor11]

I was actually just using this for once lol. Worked fine for me on 8.1.1. Try holding the home and sleep button at the same time until you see the Apple logo.

 

[amitabhbansal]

did that already but nothing worked, and the main thing is its happening in all phones

 

[Enjoylife1788]

What's your service provider?