Problem

[jerseymick]

Can't change ring duration or switch on or off voice mail with correct codes. When i attempt these actions i always get this message after dialling the relevant code. Call forwarding connection problem or invalid MMI code when no reply for all speech services. Tried new sim but same issues and even o2 shop couldn't help! This issue is on an unlocked Samsung galaxy a3 on a monthly contract. Anyone with any ideas to sort problem would be appreciated. Thanks.

[Cleoriff]

@jerseymick

Have a look at this thread and see if it helps

https://community.o2.co.uk/t5/How-to-Guides/All-you-need-to-know-about-O2-Voicemail-901/ba-p/547712

Advice about lengthening ringtone here

https://community.o2.co.uk/t5/Pay-Monthly/How-to-Lengthen-Ringtime-on-any-O2-Mobile/m-p/362784#U3627...

Hope that helps and welcome to the forum

[MI5]

@jerseymick 

You need to turn off WiFi calling in your MyO2 first 

Once that option has been disabled you will be able to use the short codes. 

You can enable WiFi calling again if needed afterwards.

[jonsie]

---

@MI5 wrote:

@jerseymick 

You need to turn off WiFi calling in your MyO2 first 

Once that option has been disabled you will be able to use the short codes. 

You can enable WiFi calling again if needed afterwards.

---

Exactly that ^^^^^

Enabling wifi calling causes all the above and also simply switching voicemail on or off is impossible. O2 systems are seemingly very limited and unable to cope when new technology is introduced In my opinion a vast amount of money needs to be invested in replacing worn out systems that weren't designed for the modern world.

[Martin-O2]

How are you getting on with this one @jerseymick? Did you find the above suggestions helpful?