Short Ringing Before Voicemail

I have the same issue with an IPhone 13 any Lebara experts available to recommend the set up please.

How do I increase time to 60 seconds from 30 secs?
My wife does have 60 seconds on her lebara phone, why can't I?
We both use lebara

KingM1 I had found this on samsung's forum - if you have not tried the below steps already!
To extend the ring time for incoming calls, please could you try the following steps?
> Open the Phone app.
> Select "Keypad".
> Type **61*321**00# on your keypad, making sure you replace 00 with the number of seconds you want your phone to ring for.
For example, you would enter the code as **61*321**30# in order for your phone to ring for 30 seconds before diverting to voicemail. You can set this to 05, 10, 15, 20, 25, or 30 seconds.
> After you have entered the code, press the Call button. After a few seconds, you will see the following message:
"Call forwarding
when no reply
Registration was successful.".
This is confirmation that the ring time has been changed. Click "OK" to clear this message and you're all done.

Hi Community, I am having a similar problem, and have tried Pri2025's suggestion but the message then received after inputting the 30 second code is
"Call forwarding
when no reply for All Basic Services
Connection problem or invalid MMI code"
Any alternative suggestions please?