how can i increase the amount of ringtime before forwarding to voicemail

[voisin]

WE struggle to answer the phone before calls are forwarded to voicemail how can we increase the amount of time that the phone rings for 

[Cleoriff]

@voisin 

Info here Guide:How to Lengthen Ringtime on any O2 Mobile 

[Enlli]

Switching down  to 2G is best May not work on 4G

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