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Gigafast VOIP / SIP with Grandstream HT801 ATA

4: Newbie

Hi all,


I'm attempting - like others before - to get the Vodafone VOIP that comes with gigafast with equipment other than the supplied Vodafone router. I've already successfully got my broadband working on a 3rd party Asus router, so I got myself a Grandstream HT801 ATA phone adaptor to attempt to do the same with the phone.


I've managed to get my Voip (SIP) credentials from tech support:

  • A username in the form voiXXXXXXXXX
  • A mixed case alphanumeric password
  • A value called ‘SIP’ which is the same as the username
  • A registration server -
  • A primary SIP server - xx.xx…


Those details have been entered into the ATA adapter, and I've done these additional steps to attempt to get it working:

  • I’ve got the UDP ports open for SIP and RTP (5060 & 5004) on my router
  • I’ve turned off anything VoiP related on the server (SIP ALG etc)
  • I’ve got NAT Traversal set up to use a public STUN server ( - set in the grandstream adaptor


With all this, my port status remains unregistered. However - something is working, as I started getting phantom calls from sipvicious (dead air on 100, 1001 etc). So much so that I’ve been in and disabled / enabled the settings mentioned here:


And that’s stopped them from ringing the phone every 30 seconds.


So I think that I've 95% of it sorted - but need help with the additional 5% to get it to register. I know that when I got my broadband details, the customer services guy who gave them to me failed to tell me that the userid for that required '' adding to the value he gave out. Or that the VLAN ID was 911... so there's the possibility that this could be a similar situation. As I mentioned above the SIP user is just 'voi' followed by a string of numbers - so I wonder if there's an '@something.something' to be added on to that.


Any help appreciated.




3: Seeker
3: Seeker

Did you ever solve your issue - if so can you post your solution here?

3: Seeker
3: Seeker

Could you post a screenshot of your HT801 settings?

2: Seeker
2: Seeker



Can you tell me how you got your SIP credentials out of tech support? I've called a couple of times, and the front line agent has also gone through to second line, and they've all said they're unable to find or give me the details?


In terms of making it work, there may be a problem that's not easy to fix. According to a thread on Reddit the Vodafone router sends specific SIP Headers in the negotiation, one of which is the Serial Number of your router, and the other is the User-Agent of the Router. Without that, it doesn't seem to work. I'm *guessing* this is a strategy to reduce brute force attacks on their VoIP proxy. The other details in that post tally up with what you have been given.


If you're snooping your SIP traffic, you should see that it's using an IP address of as a proxy, and trying to register to sip:(your sip is beginning voixxxx) At my end, without the right SIP headers being set, and without the right credentials, it's just being ignored and timing out.


In my case, I was transferred to technical support and was thankfully put to a UK-based agent, who understood what I was asking for.


Explaining that I was using my own equipment, I simply asked for the VOIP details and they were given to me. Bear in mind that BT OpenReach messed me around for a month before connecting me, so the tech support probably thought she owed me a favour and decided to give me the credentials without hesitation.


I tried to use the credentials on my HT801, but couldn't get it to register, so I gave up, and purchased a VOIP number from I do miss my old number though, so if you have any way to make it all work, I'd love to set mine up.

I might qualify for the same sympathy then - it took OpenReach 6 visits over 8 weeks to eventually find the fibre and get it to my house.


I've called 0808 003 4515, and both times been put told no-dice (after apparently a referral to second line), and they both times sounded like they understood exactly what I wanted and wanted to help.


In parallel, it seems that it might be an even bigger challenge. I have a FreePBX install, and I've been told (by a FPBX dev) that it's possible to fix the User-Agent header to be right (although it'll be sent to all our VoIP providers), it's currently not possible to configure the X-Serialnumber: header to be sent on a REGISTER request. So unless I fancy getting the Asterisk source code, hunting that down, adding it to the code base, compiling it and setting it up - it isn't possible to do.


WHY Voda have to make it so hard, I don't know, other than trying to find more ways to keep SIP-script-kiddies at bay.

I've followed all the instructions in this thread. I get a dial tone and the phone rings when I call from a mobile, however, there is no audio. Calls work without a problem with the Vodafone router.

16: Advanced member
16: Advanced member

Let's just check a few things. 

Have you set user agent as "Vox 3.0" (without the quotes)?

Are you definitely using vodafone's dns?

Is your port forwarding correct? UDP 5065 to 5065 and UDP 10000 to 10000.

Do you have a static IP or are you using STUN?

PCMA for audio? 

I've set user agent as "Vox 3.0" without quotes.

According to my router, DNS is as follows which I believe is Vodafone's DNS.

I've forwarded 5065 to 5065 and UDP 10000 to 10000.

Using static IP which I've double checked.

Yes, PCMA for audio.

16: Advanced member
16: Advanced member

Should be You can also try

What router do you have? Have you set up any dns diverts?