Sponsored Links

VOIP incoming call issues

Route66

Regular Member
I bought a grandstsream HT812 and have set it up with A&A. It works fine for calling out but after a short period will no longer receive calls. If I place an outgoing call, incoming calls will again work for a short time.

Currently it's linked to 4G+ internet via a tp link MR600 and a lebara sim.

It's as though the incoming connection goes to sleep. I've played with:
Registration expiry time
SIP OPTIONS/NOTIFY Keep Alive Interval
stun server

For all of these I have set it to the lowest time hoping that the grandstream will work to keep the connection going from my end.

As it's 4G+ router I know I wont have a public IP, but again it works for outgoing all the time and incoming for a short period. It has been suggested that my network operator may be closing NAT sessions aggressively, which is why incoming calls fail after short time.

Can anyone shed any light or help me to get this to work? Is the problem likely a network operator issue and if so would switching to another network, such as three, fix it?
 
Usually a keep alive will maintain an open connection but it does sound like it is losing the incoming route and that might be due to them timing out NAT connections in a short space of time, or they are ignoring keep alives and not resetting the timeout for keep alive packets, i.e. they don't want people hogging ports. Also AA have more than one VoIP server, so it is possible incoming calls are arriving from a different IP address which will not be able to find a route back to you. With a typical broadband connection you can just add a firewall/forward rule for all their servers, but that isn't an option if you are behind CGNAT (i.e. no public IP address).

Do you also get an IPv6 address?
 
Sponsored Links
The IPv6 section in my router is blank, apart from WAN interface name = LTE and MAC address.
Yes you will not have an IPv6 address with Lebara, only CGNAT which is problematic for VoIP.

There are some details here that might help https://support.aa.net.uk/VoIP_Firewall

The main problem is the source IPs as A&A use load balanced servers so I think even if you are registered with one of their servers and a keep alive keeps a route open, an incoming call might originate from a different server of theirs with a different address, and this has no way of getting back to you via CGNAT. It could be when you first register the load balancing is a bit sticky so you get calls routed back from the same IP address you first connected with, but after a while it does a round robin to another server, and incoming calls then stop coming through as your keep alive is keeping an incoming route open to the wrong server. I had these issues with Sipgate on IPv6, it would stop working after a while for incoming calls so it needed a firewall rule to allow all incoming connections from Sipgate's entire IPv6 range and issue solved, but I'm not on CGNAT so that would work.

You could try speaking to A&A to see if they can help but I suspect they will just say not a supported configuration, as things you might need to change or firewall rules you need to add aren't under your control.
 
I'm still relying on my old copper BT for the number I have had for thirty plus years. I pay over the odds but it does work.

I have Lebara broadband and have tried a Grandstream 801 on Sipgate basic. It works with their number.

Worrying about Sipgate losing interest in me as a freebie user I have been considering moving to A&A for the day I have to move my landline. Will I be facing the same problem with A&A as the OP?
 
I'm still relying on my old copper BT for the number I have had for thirty plus years. I pay over the odds but it does work.

I have Lebara broadband and have tried a Grandstream 801 on Sipgate basic. It works with their number.

Worrying about Sipgate losing interest in me as a freebie user I have been considering moving to A&A for the day I have to move my landline. Will I be facing the same problem with A&A as the OP?

Lebara broadband (assuming you mean their broadband product and NOT a SIM card in a router) is different to Internet over mobile networks so you shouldn't see a problem, or at least will be able to make the necessary settings at your end if you do.
 
It appears to be the CGNAT in the network closing the port after a timeout. You have a few options:
1) ditch Lebara and go to Three, their 3internet APN dishes out public IP addresses and VoIP will work without any issues (that's what I am using since early January without any problems).
2) get an L2TP tunnel, e.g. from A&A, the Lite version costs £2.00 per month but you might have to fiddle with the routing at your end, i.e. VoIP over L2TP, everything else direct.
3) go for IPv6, I heard that EE support that but it may not be easy to get it all configured.

or keep on debugging:

incoming calls will again work for a short time.
@Route66 can you clarify this statement, please. Does that mean that an incoming call drops (mid-call) after a while or that several incoming calls work for a "short time"?
And approx. how many minutes/seconds is a "short time"?

It's as though the incoming connection goes to sleep. I've played with:
Registration expiry time
SIP OPTIONS/NOTIFY Keep Alive Interval
stun server

Correct, the most likely cause is the CGNAT deleting the NAT rule for SIP after the "short time". SIP OPTIONS should fix that issue if the interval is short enough.

I would not change the Registration expiry time as it creates too much traffic. You will most likely need STUN so the Grandstream can figure out the public (external) IP for your connection.

Can you also let us know how you connect to 4G. I assume you have a 4G router which itself uses NAT, so you have double NAT which does not help either. But you should be able to set up port forwarding for UDP port 5060 on your 4G router which mitigates that issue.
 
Sponsored Links
Lebara broadband (assuming you mean their broadband product and NOT a SIM card in a router) is different to Internet over mobile networks so you shouldn't see a problem, or at least will be able to make the necessary settings at your end if you do.
Mine is a SIM card in a Huawei router.
 
Mine is a SIM card in a Huawei router.
You will likely have similar issues. SIP doesn't like NAT for various reasons, there are a few work arounds and hacks that make it work for most people, however over a mobile network you often end up on their own private network that doesn't look out onto the Internet directly, this is called CGNAT (Carrier Grade NAT). This means you have no direct control over allowing incoming traffic as you are not in control of your own Internet connection. This is all down to the lack of IPv4 addresses, so there aren't enough to give every person with a mobile phone (or router going over a mobile network) their own unique IP address. Without a unique IP address, connections find it hard to reach you when they are incoming from the Internet and all sorts of strangeness can happen.

IPv6 would resolve this issue as there is essentially an inexhaustible supply of unique addresses, so you would be reachable from the Internet. However Lebara doesn't do IPv6, yet anyway.

It might be the case of moving to a different provider, Three will give you a public IP address, and EE do IPv6.
 
What a bore, Phil.

I used Smarty for a while and got good speeds but moved to Lebara as they were more reliable. I could go back to Smarty and that would save me £9 a month if they still do the £16 deal.

My inclination is to pay the cheeky BT landline rental a bit longer but I do realise I will have to make the jump sometime.
 
Thanks for all the input.

I've been testing this at home where I have a MR600 with a lebara sim. I intend to use it at work where I have a MR600 with a three sim. I also still have TalkTalk BB at work, but plan to get rid once I get the VOIP running and port the number.

Anyway I took it all to work and tried it with the TalkTalk router and it worked fine (I had to disable ALG SIP though). I then tried the MR600 with a three sim and it also worked fine.

It's good job I didn't spend several hours trying to get it to work at home, oh wait a minute...

Thanks again for all the help.

EDIT to answer the question about incoming calls I didn't answer most of them, but when I did they appeared to stay connected. I was able call inwards for a very short period, probably less than a few seconds after a reboot, or a call outwards. This morning before I took everything to work I tried it again but this time no incoming calls worked, even if I phoned out first and called back instantly, so I'm not sure what changed overnight.
 
Sponsored Links
I have Softphone on my Flip 4 and it is configured to my Sipgate Basic 0203 number.

The Flip 4 will be getting the broadband from my Lebara Sim in the Huawei.

I haven't used Sipgate for months but the Flip 4 picked up the incoming Sipgate call instantly. Why did it not have the same problem as the OP - or is it that the Flip 4 and a Grandstream address Sipgate differently?
 
I have Softphone on my Flip 4 and it is configured to my Sipgate Basic 0203 number.

The Flip 4 will be getting the broadband from my Lebara Sim in the Huawei.

I haven't used Sipgate for months but the Flip 4 picked up the incoming Sipgate call instantly. Why did it not have the same problem as the OP - or is it that the Flip 4 and a Grandstream address Sipgate differently?
The sorts of issues seen can be intermittent. Also Sipgate is a different provider, and in my experience they seem to use more sticky IPv4 addresses, by that I mean incoming calls come from the same IPv4 address that your end is constantly keeping awake, so they can find a way back to you. (They don't do this with IPv6 and calls do come in from different servers but then IPv6 is easy to setup so it will work perfectly that way.)

Also Lebara/Vodafone may have rules set up for some of the most popular VoIP providers to make things more likely to work okay across their CGNAT, whereas A&A may not be in that list. The thing is we just don't know all the ins and outs, and that is the main issue with CGNAT, it's all a black box.
 
Fascinating Phil,

We have a weird system here based on a Panny DECT hub that takes our BT landline and connects by Bluetooth to my and my wife's cellphones. In anticipation of the removal of the BT copper feed I bought a Grandstream ATA jobbie and established that it could be fed into the Panny hub. So I can port my BT number to Sipgate and the tests I did last year showed I could use the Grandstream to feed that number into the Panny.

What the OP was saying about losing incoming calls worried me as the only reason we keep that number is because friends of old know it. I will keep doing the tests.

However once I get my wife on to a smart phone I presume I can put Softphone on it and both her and my phones will then pick up Sipgate (with our BT number by then ported) and we can then do without the Grandstream.

Let's hope Sipgate keep things the way they are!
 
I assume you used the "3internet" APN?
I'm guessing so. It's another MR600 (I have one at home with lebara and one at work with three) which was set up with the three sim in. I've never really looked in detail at the one at work as I haven't started to fully utilize it yet. It's just ready for when I bin talktalk off.

The problem with this issue is that beyond self testing regularly the only way to know it is happening would be when people start reporting not being able to call us. The user would have no idea as all outgoing calls will work. So I hope it is just a lebara issue and not something that rears its head again.

Given the knowledgeable people here I now have another question regarding the MR600 with three sim, but I will post it separately.
 
Sponsored Links
Top
Cheap BIG ISPs for 100Mbps+
Community Fibre UK ISP Logo
150Mbps
Gift: None
Virgin Media UK ISP Logo
Virgin Media £22.99
132Mbps
Gift: None
Vodafone UK ISP Logo
Vodafone £24.00 - 26.00
150Mbps
Gift: None
NOW UK ISP Logo
NOW £24.00
100Mbps
Gift: None
Plusnet UK ISP Logo
Plusnet £25.99
145Mbps
Gift: £50 Reward Card
Large Availability | View All
Cheapest ISPs for 100Mbps+
Gigaclear UK ISP Logo
Gigaclear £17.00
200Mbps
Gift: None
Community Fibre UK ISP Logo
150Mbps
Gift: None
Virgin Media UK ISP Logo
Virgin Media £22.99
132Mbps
Gift: None
Hey! Broadband UK ISP Logo
150Mbps
Gift: None
Youfibre UK ISP Logo
Youfibre £23.99
150Mbps
Gift: None
Large Availability | View All
Sponsored Links
The Top 15 Category Tags
  1. FTTP (6027)
  2. BT (3639)
  3. Politics (2721)
  4. Business (2440)
  5. Openreach (2405)
  6. Building Digital UK (2330)
  7. Mobile Broadband (2146)
  8. FTTC (2083)
  9. Statistics (1901)
  10. 4G (1816)
  11. Virgin Media (1764)
  12. Ofcom Regulation (1582)
  13. Fibre Optic (1467)
  14. Wireless Internet (1462)
  15. 5G (1407)
Sponsored

Copyright © 1999 to Present - ISPreview.co.uk - All Rights Reserved - Terms  ,  Privacy and Cookie Policy  ,  Links  ,  Website Rules