VoLTE Setup fail due to 486 busy reason

Hello all.
Here VoLTE Setup fail pegs for 486 busy reason…
Is it temporary issue in VoLTE network?

Can anyone please explain this?

Very near to site sometimes 488 not acceptable; here sip message also trigger for setup fail?

Usually 486 is when party B rejects the call.
Do you have b side log?
486 is not considered as a setup failure.

That is b site I mean mt side.

This is normal network behaviour when b side rejects the call.

486 Busy Here is generally seen when the other party has rejected the call.
Other possibility is that if the MT party has blocked the number, it may send 486 Busy here to the MO side.
It generally doesn’t account for any setup failure, however having MT side logs will make it more clear.