Since my post of 22 Feb Fairphone have recognised a problem with the microphone operations in handsfree/Whattsapp type use. This means there is no noise cancelling function and the echos may be somehow related, though I’m not at all clear how they could be.
On the delay side of the problem I’ve only had that in conjunction with the echo, where the echo was louder than the call, making it appear there was delay, but never a delay of more than a second.
Delays I imagine are more to do with the network structure having to reroute signals sometimes. and of course as previously pointed out having to encrypt and decrypt doesn’t help.