2degrees Fritzbox ignoring incoming call after an ~20mins

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fe31nz

1232 posts

Uber Geek

#2971871 22-Sep-2022 23:31

TechnoGuy001:

Long story short, for the Ubiquiti Dream Machine (UDM), all I had to do was login to its UniFi portal and tick "SIP" under Conntrack Modules. Then gave the Fritzbox a reboot and haven't have any issues since.

Settings > Firewall & Security then under "Conntrack Modules" tick SIP.

Wow! SIP support in a router that actually works! Most of the time, turning on a router's SIP support will only make things worse, as the SIP protocol is actually insanely complex and there are many different interpretations of what each bit of it actually does. Which means that the SIP support in a router has to be using exactly the same interpretations as the provider of the SIP connection is using, and that rarely happens.

Tinkerisk

4228 posts

Uber Geek

#2971886 23-Sep-2022 05:36

Recently I configured an old FritzBox 7170 (as an VoIP-ATA for 2 analog phones and a fax) behind an ERL for a customer. Still works flawlessly.

The tricky Telekom MagentaTV IPTV firewall handling on the ERL works as well (IGMP3 VLAN switch is mandatory).

- NET: FTTH, OPNsense, 10G backbone, GWN APs, ipPBX
- SRV: 12 RU HA server cluster, 0.1 PB storage on premise
- IoT: thread, zigbee, tasmota, BidCoS, LoRa, WX suite, IR
- 3D: two 3D printers, 3D scanner, CNC router, laser cutter

Tinkerisk

4228 posts

Uber Geek

#2971888 23-Sep-2022 06:00

fe31nz:

Wow! SIP support in a router that actually works! Most of the time, turning on a router's SIP support will only make things worse, as the SIP protocol is actually insanely complex and there are many different interpretations of what each bit of it actually does. Which means that the SIP support in a router has to be using exactly the same interpretations as the provider of the SIP connection is using, and that rarely happens.

Well, I ASSUME the SIP conntrack module is disabled by ticking the SIP checkbox for the UDM. At least for the ERL, I had to disable the SIP module by the command

set system conntrack modules sip disable

I did not open any ports at the ERL for VoIP (but I have to re-check this) and the complete SIP handling is done by the Fritzbox. ;-)

(the same applies to a Cisco ATA I had in use with an ER4 in the past).

Tinkerisk

4228 posts

Uber Geek

#2971890 23-Sep-2022 06:23

duffles:

The Fritz will be sending a SIP keep-alive every ~5 minutes or so and your UDM will be stopping this, …

This should be set at the Fritzbox to it’s fastest setting, I think it is 30sec. This was my problem I faced once which sounds similar to this post.

duffles

100 posts

Master Geek

Trusted

2degrees

#2971986 23-Sep-2022 09:35

Tinkerisk:

This should be set at the Fritzbox to it’s fastest setting, I think it is 30sec. This was my problem I faced once which sounds similar to this post.

psend and keep-alive, not quite the same. My (and OP) psend is set to 20ms. Which is what it should be.

They say he carved that spoon himself.. From a bigger spoon..
Any comment made here is my own and should not be taken as that of my employer. You've seen one of these statements before.

TechnoGuy001

853 posts

Ultimate Geek

ID Verified

#2972023 23-Sep-2022 10:48

Tinkerisk:

fe31nz:

Wow! SIP support in a router that actually works! Most of the time, turning on a router's SIP support will only make things worse, as the SIP protocol is actually insanely complex and there are many different interpretations of what each bit of it actually does. Which means that the SIP support in a router has to be using exactly the same interpretations as the provider of the SIP connection is using, and that rarely happens.

Well, I ASSUME the SIP conntrack module is disabled by ticking the SIP checkbox for the UDM. At least for the ERL, I had to disable the SIP module by the command

set system conntrack modules sip disable

I did not open any ports at the ERL for VoIP (but I have to re-check this) and the complete SIP handling is done by the Fritzbox. ;-)

(the same applies to a Cisco ATA I had in use with an ER4 in the past).

Yeah, it's not totally clear what it does on the UDM, even reading the tool tip. (at least for me, though I am a bit sleepy so could be that too)

Tinkerisk

4228 posts

Uber Geek

#2972181 23-Sep-2022 15:43

duffles:

Tinkerisk:

This should be set at the Fritzbox to it’s fastest setting, I think it is 30sec. This was my problem I faced once which sounds similar to this post.

psend and keep-alive, not quite the same. My (and OP) psend is set to 20ms. Which is what it should be.

The (unbranded vanilla) 7170 has nothing else to configure except SIP server session keep-alive. (seems the FB7590AX either)

Sharesies

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Tinkerisk

4228 posts

Uber Geek

#2972268 23-Sep-2022 18:16

Perhaps I should also mention that everything has obviously been done right if the rather delicate analogue fax send and receive operation via IP runs smoothly and reliably in a small company. It has been doing so for 9 months.

duffles

100 posts

Master Geek

Trusted

2degrees

#2972301 23-Sep-2022 19:55

Tinkerisk:

The (unbranded vanilla) 7170 has nothing else to configure except SIP server session keep-alive. (seems the FB7590AX either)

My unbranded (AVM) FB7590AX shows exactly what OP showed, where the packet size send (psend) is set to 20ms 😉
SIP server session keep-alive is initaited by the far side, in this case 2degrees. It simply requires a response from the device negotiating the SIP registration, in this case the Fritz!Box.

Glad to see OP got the issue sorted and voice is working happily 🙂

Cheers

They say he carved that spoon himself.. From a bigger spoon..
Any comment made here is my own and should not be taken as that of my employer. You've seen one of these statements before.

Tinkerisk

4228 posts

Uber Geek

#2972302 23-Sep-2022 20:03

duffles:

My unbranded (AVM) FB7590AX shows exactly what OP showed, where the packet size send (psend) is set to 20ms 😉

Maybe pre-set but the user still can‘t configure it.

The "30 seconds" in the Fritzbox menue is the time that a router installed in front of the Fritzbox maintains the temporary (therefore no explicit port forwarding) automatic port forwarding rules to the STUN - I checked this, no port forwarding for VoIP in the ERL. Whether that involves a psend of 20ms or a blue neighbor's car is completely irrelevant - the user can‘t configure psend in the Fritzbox by himself freely.

If someone increases the Fritzbox time to e.g. 5 minutes, an EdgeRouter will break the connection because it can't do anything with it, then it ends with 'keep-alive' or 'psend' or '[insert here]', no matter which provider it is connected to.

BTW: AVM itself recommends selecting 30s if you do not know how long the router to which the FRITZ!Box is connected will maintain the temporary port forwarding rules.

duffles

100 posts

Master Geek

Trusted

2degrees

#2972327 23-Sep-2022 21:59

Tinkerisk:

The "30 seconds" in the Fritzbox menue is the time that a router installed in front of the Fritzbox maintains the temporary (therefore no explicit port forwarding) automatic port forwarding rules to the STUN - I checked this, no port forwarding for VoIP in the ERL. Whether that involves a psend of 20ms or a blue neighbor's car is completely irrelevant - the user can‘t configure psend in the Fritzbox by himself freely.

If someone increases the Fritzbox time to e.g. 5 minutes, an EdgeRouter will break the connection because it can't do anything with it, then it ends with 'keep-alive' or 'psend' or '[insert here]', no matter which provider it is connected to.

The 20ms on psend is the amount of times the device will allow a SIP packet to be sent/received. Which means, if the Fritz isn't the edge device, the device it is hanging off will need a handful of config changes to ensure that it is not blocking the traffic in a panic. This setting has an impact on voice quality and not so much actually keeping the session active. So while you can have this set to 30ms or 5 minutes to have a short converation on a telephone or send/recieve a fax, if you were to use the service with limited bandwidth or attempted any or many smart services, you'd find that the voice quality will sound like you're speaking through the vent of an air conditioner.
The "keep-alive" that I refer to is the INVITE / ACK SIP requests that are sent/received between the CPE and SBC required to keep the session active. Not really relevent to psend values in the context of this thread.

If you were to set the psend to 5 minutes, as you say, I think you would find that your voice quality will be on par with toilet rolls connected by string. And if you expect a SIP session to remain active without any sort of acknowledgement for 5 minutes, the voice network you're connecting to is certainly setup in an interesting fashion. 🙂

EDIT: corrected typo.

They say he carved that spoon himself.. From a bigger spoon..
Any comment made here is my own and should not be taken as that of my employer. You've seen one of these statements before.

Tinkerisk

4228 posts

Uber Geek

#2972344 24-Sep-2022 00:19

Tinkerisk:

duffles:

The Fritz will be sending a SIP keep-alive every ~5 minutes or so and your UDM will be stopping this, …

This should be set at the Fritzbox to it’s fastest setting, I think it is 30sec. This was my problem I faced once which sounds similar to this post.

Your words, my words and what you made of it without being asked for turning my words to what I've never said. If you are bored, please proceed (but not for me, because my autoconfig works already). If your's works as well, just be happy. I'm fine with the TO, what ever works for him.

@TechnoGuy001

I don't know if your FB box/fw supports it, but if you can, enable the "Encryption" menu item on the Fritzbox if your provider supports it. Mine does.

duffles

100 posts

Master Geek

Trusted

2degrees

#2972352 24-Sep-2022 00:47

@Tinkerisk I think there has been a misunderstanding in terminology or jargon.
If you'd like to discuss Fritz!Box and SIP, feel free to DM me. Not so long ago, I was part of the team at 2d that tested various Fritz!Box and Fritz!OS specifically for voice and PBX nonsense.

Regardless, OP's issue is resolved. Job done. 🙂

They say he carved that spoon himself.. From a bigger spoon..
Any comment made here is my own and should not be taken as that of my employer. You've seen one of these statements before.

nztim

3819 posts

Uber Geek

ID Verified

Trusted

TEAMnetwork

Subscriber

#2972433 24-Sep-2022 09:33

fe31nz:
nztim:

Argh, this is why, all RSPs should (at least if requested by the customer) offer ONT based Voice, it will remove these headaches if people want to use there own router.

The ONT POTS ports are analogue Plain Old Telephone Service. They are fine for people who just want to plug in their old analogue phone, but VOIP all the way to a VOIP phone can now provide for higher quality codecs to be used.

I think you will find both the Phone port on the Fritz and on the ONT are ATA voice ports which turn Analogue based voice into SIP traffic and both support the same codecs.

Any views expressed on these forums are my own and don't necessarily reflect those of my employer.

fe31nz

1232 posts

Uber Geek

#2972869 26-Sep-2022 00:27

nztim:

I think you will find both the Phone port on the Fritz and on the ONT are ATA voice ports which turn Analogue based voice into SIP traffic and both support the same codecs.

Of course. But there are other ways to connect a phone to a FritzBox that are full digital VOIP, such as using a hardware VOIP phone, or a softphone. The most common example is the Android or iOS Fon app (from the FritzBox manufacturer). You can use any other VOIP software that you can configure to work with the FritzBox. I use the 3CX app on my laptop, and I have used the Android Linphone app too. And when you use a full VOIP connection, often better codecs are used. You can see the codecs for each call in the daily report that a FritzBox can email you if you set that option.

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