Conference Merge calls not working
As have several others, I find that merging calls is not working. It's an iPhone 7 Plus with up-to-date software v 13.6.
Selecting a second call works fine and I can switch between them properly. The 'merge calls' button is available, not greyed out, but pressing it does nothing at all: no change to either call (current or on hold), no error messages, nowt.
I'm in England, on Vodafone network with a pay monthly plan. I've checked with Vodafone that the settings are as required and that there is no constraint on the plan or the network. Judging from other threads on here, it seems to be a phone problem. (Although I notice that someone else with a similar problem was also on Vodafone, and another person had the problem only when in Europe, so perhaps there is something in the network.)
I have made sure wifi calling is switched off, and also tried with wifi entirely disabled. I have restarted the phone several times. Any further help would be much appreciated, please.
Stephen
iPhone 7 Plus