Call Ringtime Duration Increase To 30+ Seconds ?

[4rb5ta4ewsb5ew4]

I want to increase the duration of the ring to 30+ seconds, ideally 90 or 120 seconds. Is this possible ? I have followed the guide on the post below, and tried replacing the "30" with "60" but it appears 30 seconds is the maximum time possible.

https://community.o2.co.uk/t5/How-to-Guides/How-to-Lengthen-Ringtime-on-any-O2-Mobile/bc-p/1712551

[MI5 · Accepted solution]

@4rb5ta4ewsb5ew4 

30 seconds is the industry allowed maximum.

Any longer will require disabling voicemail completely.

Guide: All you need to know about O2 Voicemail 901