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Problems with Digital Voice calling iPhones

3: Seeker
3: Seeker

Is anyone else experiencing a problem when calling a mobile - specifically in my case iPhones - using the Digital Voice landline?

I have just moved over to Vodafone Broadband with Landline and whilst the broadband setup is fine, whenever I have tried calling my own and my wife’s mobile form the DV landline, the connection fails.

Sometimes the iPhone doesn't ring, sometimes it does bit cuts off when the the green answer call button is pressed. At the landline end, you hear the call ringing, but when the iPhone attempts to answer, the sound changes to a sort of repetitive ‘honking’ tone and that's it, until the landline cancels the call.

I've tried it with several different landline phones, tethered and cordless - the result is the same. The call iPhone -> DV land line seems fine.

Any clues? 


16: Advanced member
16: Advanced member


Your posts are sounding a lot like advertising for A&A.

They are not :Winking_smiley:

For you, it's easy to navigate the world of DV/SIP etc., but there are many (mainly older generation)
that have absolutely no clue what is going on and what is the best think to do ........(in order not to loose their landline number).

While in the past, SipGate was my main alternative, they have discontinued offering SIP numbers/landline to consumers :Sad_face:
but, there are still at least 2 choices for people who do not want risk loosing their landline number .....

- A&A
- NumberPeople

3: Seeker
3: Seeker

I have just come across this thread. My 90 year old mother has recently gone full fibre with Digital Voice (VOIP) and can now not call my mobile. She gets NU and I get a blipped miss call.

On further investigation I now have a a collection of around 5 mobile numbers that this happens to. The handsets are both iPhones and Android.

The key common theme is that the number is in the EE allocated range (by ofcom) and the users have ported to O2.

Every single one of those numbers fail. All other combinations (i.e. original number Voda, user on O2, original number O2 user still on O2) work. Anyone any idea how I get this info to someone who can do something about this. 

As a Chartered Electronics Engineer with nearly 40 years experience in the Comms field it is very frustrating being ASSURED by Webchat that if you can make one call out on VOIP then it isnt their end but must be the recipient. They have no concept of number porting or that it isnt one size fits all.


Hi there @lcsneil - Thanks for reaching out about this. Sorry to hear your mother is having issues making calls since making the switch to Digital Voice. We do have an internal Home Broadband team here at Vodafone who will be able to troubleshoot and assist further. Would it be possible for the account holder to reach out to them to get this sorted? They can be reached via phone on 0333 304 0191 📞 The lines are open Monday - Friday 8am-10pm or Saturday & Sunday 8am-8pm. 

@Ami Will do. I actually suspect I know what the issue is - the challenge is getting the info to someone technical enough in Voda who knows what I am talking about. 

I have done further tests and can confirm that it does appear to be limited to the EE / O2 combination. The control channel works OK which is why you end up getting a 'missed call' on the phone and then nothing else. This is I figure because the audio codec negotiation fails with the Voda<>EE<>O2 interface. 


I do have a partial  workaround for anyone else that is having the same issue. Please note though that this is when you have a family member that is trying to contact you as it relies on altering settings on your mobile phone to force the Voda network to use PSTN audio rather than HD calling or equivalent codecs over a data channel. This has been tested on Android but should also work for iPhones. Basically you have to turn off the VoLTE and also Wifi calling. This stops the phone trying to use a software audio codec that doesnt work between the two parties (Voda & O2). 

Annoyingly my Samsung Galaxy automatically switches VoLTE back on after a reboot. 
On the S10 you can find the VoLTE setting under Settings> Connections > Mobile Networks. This needs to be OFF. (Note that if it doesn't appear - such as on a Giff Gaff SIM then the network doesn't support VoLTE so this shouldn't be an issue.)

Also switch off Wifi Calling under Settings> Connections. (very basically VoLTE  or Voice over LTE is wifi calling over mobile data). 
If you switch off both those settings as least the Digital Voice of Voda should be able to get through to a ported EE number on the O2 network. 

We will need to continue to do this until Vodafone correct their audio codec negotiation settings. 

Hope this helps someone.


That sounds like exactly the problem I had with my 91 year old fathers landline phone calling my EE mobile. It took over 3 months to sort out as although EE alerted Vodaphone to the issue they refused to take any action unless the person who owns the landline made the call. My father being elderly, hard of hearing and very confused regarding techical terms and actions.. for example resetting the router was unable to engage with customer service. The only option was to make the call on his behalf although I live over 100 miles away so tricky. I tried first in Mid November durifully providing examples of attemps to call EE numbers from long suffering friends. Anyway nothing got done and I spent most of the Christmas period trying to get it sorted out still no action. They would not communicate with me unless he was present and no one until a lot later explained that I could be put on as a contact. Anyway I went to his house again Mid January and thankfully it got sorted out. However why could they not have investigated when EE alerted them in eary November? It shows a chronic lack of  professional and technical curiosity. It's like a some one noticing a house is on fire, and the Fire Brigade saying ' Sorry we will only come out to put out the fire if the person at that address calls us themself' Yes I gat there may be issues with scammers, but I was not wanting to change anything with his account or get a Netflix bundle using his payment details. I simply wanted to raise a fault that was affecting his ability to use the service that he is paying for. THERE SEEMS TO BE NO COMMON SENSE AS FAR AS THE SYSTEM OF DEALING WITH FAULTS IS CONCERNED

has this problem been fixed yet?  I don’t want to have to waste my time again contacting Vodafone when this thread has identified the problem. Has this thread been shared with the technical team? 

Hi SLP37,

No. Despite there being a "technical" workaround, the problem that Vodafones VOIP system does not work for some mobile phone systems still exists.

I do not have the technical know-how (or death-wish to call Customer Services - again). 

Forum member lcsneil has identified the problem (and suggested the workaround) and is chasing this up with Vodafone.  See his replies.

It would not hurt our cause if anyone else were to pass this thread on.


So I reported the fault via webchat. I supposedly convinced the chat host to copy and paste in my direct words for 2nd line technical support. 2nd line called me and didn't have much of a clue. I then got an email from them asking me to make some test calls. This is what I had just told them on the phone. I emailed through the complete text and test calls with details. Despite following up via email to 2nd line support. I've heard nothing back and as per my first post their technical team I spoke with clearly doesn't understand how modern VOIP technology works. 

So @Ami despite the bog standard call our helpline. Your helpline and 2nd line support didn't have a clue. As I feared reaching someone who knows what I'm talking about is nigh on impossible. 

I'm currently out of the country for the next few weeks so unfortunately won't be chasing it up. 

Let's see if anything comes off it whilst I'm away. 


Thank you for your efforts.

I have also left feedback to posting on this forum. Quoting a link to YouTube video and link to this thread.  Hoping someone from IT might read it!
Enjoy your trip.