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I upgraded from a Samsung S10 to S20 and could use conference calls/merge calls. I am no longer able to use this. When I try to add a second call it says unable to merge calls/switch calls. I have been in two different Vodafone shops and they have looked at the account and phone and cannot work out what is wrong. They put a new sim in and it still won't work.
My brother had the exact same issue on the S21 and took it to a Vodafone shop. The woman in the shop made a phone call to tech and within 10 minutes it was sorted. She said it was something that had to be changed at their end regarding the amount of people allowed on the call. When I told the guy in the shop about this he had no idea. He said as far as he could see there was nothing wrong on their end and didn't know how to fix it.
They said they had already done it but they tried it and it still wasn't working. Took the sim out and tried it on another phone and it still didn't work. Put a new sim and still nothing.
Call waiting is on. Spoke to Vodafone through messenger and they couldn't find anything. Told me to contact Samsung support.
Samsung support told me it was nothing to do with them it was a problem with the conference call set up with Vodafone so no further on and nobody seems to know where the problem lies.