Ringtime before connection to voicemail

[mispeltyuoth]

I've looked at previous posts on here and elsewhere in the web to see if I can extend the time before voicemail kicks in. I understand that the time is set by the networks - at 20 seconds - but some people claim to have been able to extend the time to 30 seconds by putting in a code - *61*+447953223571*11*30#. I've tried this while connected directly to the network and with wifi calling on and get the same result both times: 

I've also tried *10*30# without success.

The thing is, 20 seconds isn't long enough; can someone confirm if this is 'set in stone' or has anyone got the code or similar to work recently? 

[Keith_Beddoe]

https://community.bt.com/t5/Archive-Staging/Extending-ringing-time-before-voicemail-activates/m-p/16...

[mispeltyuoth]

Hi @Keith_Beddoe 

As I said, I've read previous posts and followed the guidance there and shown what my result was. That thread is 6 years old hence my question being has anyone recently succeeded. 

[Les-Gibson]

Page 17 of the user manual "You can also record your own personal greeting or change the ringer delay from this menu. "

[mispeltyuoth]

Page 17 of what user manual?

[Les-Gibson]

https://www.bt.com/content/dam/bt/help/digital-voice/advanced-phone/BT-Advanced-Digital-Home-Phone-U...

[Les-Gibson]

Voicemail (1571) This service answers your calls when you can’t. Callers can leave a message, which you can hear by dialling 1571. If you’ve got messages waiting for you to listen to, you’ll see lit up and hear an alert (if set). You can also see the number of messages waiting for you. 118am Handset 1 3 Menu Press Calls to listen to your messages. You can also record your own personal greeting or change the ringer delay from this menu.