How can I extend how long incoming calls ring for iPhone?

How can I extend how long incoming calls ring for iPhone?

It is your carrier that determines the number of rings on your iPhone. Contact your carrier.

Most carriers offer an option to set the number of rings from 1 to 8, for example.

iPhones (and most smartphones) do not have a built-in setting to change the ring time or number of rings before a call is forwarded to voicemail. That behavior is controlled entirely by your cellular service provider (carrier), not the phone or its iOS settings.

Some service providers do allow changes using USSD code **61*YOUR_VOICEMAIL_NUMBER**30#

• Replace 30 with the number of seconds you want (in multiples of 5, up to 30).
• Replace YOUR_VOICEMAIL_NUMBER with your carrier’s voicemail number.

This does not apply to Live Voicemail.

depending on your country and provider...

https://en.m.wikipedia.org/wiki/Call_forwarding