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[Resolved] FPL - Calling from Landline ends up in VM

PostPosted: 07/03/2021
by GiJoeBlack
Hello All,

Just over a month I have been running into challenge calls from Landlines and certain cell phone providers (eg Rogers) are directed to VM. I have reviewed other users experiencing similar challenges and have attempted to set the ATA to factory defaults and followed config guide provided in this forum to setup to no fix. I own ATA SPA2102 (v5.2.12), Asus EA6900 (v386.1_2 - Merlin), ISP Fido - Modem from Fido set in Bridge Mode. It should be noted, callers from bell, telus cell network are able to call fine while callers from Rogers are routed to VM. I have followed other suggestions provided to other users in forum but have not been able to resolve the issue. My hope is some very knowledgeable folks here can provide their 2 cents resolve this issue. It should be noted, nothing from provider, setup has changed to result into the issue.

Any help is greatly appreciated. Look forward to your assistance.

Re: FPL - Calling from Landline ends up in VM

PostPosted: 07/03/2021
by Liptonbrisk
Rogers numbers have no issue calling me on my FPL accounts.

Note that for the steps below, the ATA settings require select "admin" and "advanced" for some settings to appear.
Follow the steps down the list, step by step:

1. What is the brand and model modem you're using?

2. Do not use "+NAT Helper", which is the ALG, for SIP Passthrough in Merlin.
This is the most likely cause of your problem. See here: viewtopic.php?f=8&t=20182#p78916.
Fido cell uses Rogers' cellular network.

Login to Merlin.
Navigate to Advanced Settings-->WAN-->NAT Passthrough-->SIP Passthrough

Change to "Disabled".
("Enabled" works for me as well, but I do not use "Enabled + NAT Helper").

+NAT Helper is a security risk. ... ost-657216
RMerlin wrote:The NAT Slipstream attack is the one that uses ALGs helpers to potentially compromise clients. I recommend making sure none of the settings on the NAT Passthrough page is set to "Enabled + NAT Helper", they should be either "Enabled" or "Disabled". I haven't tested this, but I would expect that ensuring NAT helpers are disabled to be enough to prevent this attack vector.

Those ALG are generally not needed by modern clients. For instance, I have both an ATA (for my home phone) and a direct IP phone (for work) here, both work fine without the need for an ALG helper.

Click "Apply"

3. In Merlin, under General-->Tools

a) Change UDP Timeout: Unreplied to 15 seconds, provided NAT Keep Alive Interval in the ATA is set to 20 seconds (see step 6d below).
b) Change UDP Timeout: Assured to 115 seconds, provided that Reg Retry Intvl in your ATA is set to 120 seconds (see step 9 below).

Refer to point D from viewtopic.php?f=8&t=20199#p78976 for the reason why you should do this.

4. Ensure that you've not accidentally enabled Caller ID block on your ATA. Dial *68 to remove caller ID blocking on all outbound calls.
Don't use "Anonymous" for display name in your ATA. Don't use or accidentally dial *67.

In your ATA under look for, under Voice-->Line (whichever one you're using for FPL)-->Supplementary Service Subscription-->Supplementary Service Subscription-->Block CID Serv: change to no, and click "submit"

This step is not related to your issue at all, but some have reported fast busy on outgoing calls with that setting enabled.

5. . Specify a high random SIP port in your ATA between 30000 and 60000.
Navigate to Voice-->Line 1 (or whatever you're using for FPL)-->SIP settings, change SIP Port to a random number between 30000 and 60000.
Just pick a random number in that range.
Do not use the same random SIP port for any other Line. Always choose a different random local SIP port for each Line you're using.

Using a high random SIP port may help to bypass SIP ALG, and it also helps to avoid SIP Scanners (or hackers).

Click "Submit All Changes"

6. In the ATA, navigate to Voice-->SIP tab-->NAT Support Parameters, and make sure that the following settings are enabled:

a)Handle VIA received-->yes
b)Handle VIA rport-->yes
c)Substitute VIA Addr-->yes
This helps to ensure the RTP audio stream is being sent to your WAN IP as opposed to your LAN IP.

d) NAT Keep Alive Interval--> 20 seconds

e) click "Submit All Changes" button

7. In the ATA, Navigate to Voice-->Line (whichever you use for FPL)-->NAT settings
a) NAT Mapping Enable should be yes
b) NAT Keep Alive Enable should be yes
c) NAT Keep Alive Msg should be $NOTIFY

d) click "Submit all changes" button if changes were made

8. Log in your ATA, navigate to Voice-->Line-->Proxy and Registration-->Register Expires needs to be 3600 seconds (it probably already is set to 3600)

9. Navigate to Voice-->SIP-->SIP Timer Values (sec)
Reg Retry Intvl should be 120 seconds

Click "Submit all changes" button if changes were made

Many older guides for FPL don't include this setting.

10. In your ATA, under Voice--Line(FPL)-->Proxy, use "" (without the quotation marks). Remember 6060 is the proxy server port--and not the local sip port.

11. Proper device reboot order is always modem (wait for it to be fully up before turning on your)-->router (ensure Wi-Fi SSIDs are populated first on your devices)-->ATA (wait for router to be fully up and running before turning on ATA). That's always proper device reboot order. Reboot your devices in that order now.

12. Lastly, ensure, after logging in at that

i) SIP Status shows "connected", and
ii) SIP User Agent reflects a device that own and recognize. If you don't recognize the SIP User Agent, chances are you've been hacked.

13. Test incoming calls

Note that only one registration per FPL account is allowed at any time. When there are multiple devices/softphones using the same account, only the most recent registration is valid. The previous device will lose registration, and, consequently, incoming calls will not work on it. This is especially important to consider if someone else is using your SIP credentials (username and password) that are found after logging in at or if you're trying to register your FPL account with a smartphone SIP app or with another device. Registration is required for incoming calls. It is not required for outgoing calls. A more significant concern, though, is that multiple registration attempts can lead to temporary IP bans. The more devices being used can make the temporary ban happen more quickly. Note that each time you reboot or restart your ATA or SIP app, it's attempting to register with Freephoneline again. Multiple registration attempts within a short period can result in temporary IP ban. Each time you reboot your ATA it's attempting to register with FPL's proxy server.

Re: FPL - Calling from Landline ends up in VM

PostPosted: 07/03/2021
by GiJoeBlack
Appreciate the prompt response. I will go thru the checklist that you have provided and revert back with my findings/update. And yes to ans your question related to Modem, its CGN3U from Fido.

Re: FPL - Calling from Landline ends up in VM

PostPosted: 07/03/2021
by Liptonbrisk
GiJoeBlack wrote: its CGN3U from Fido.

The brand is Hitron.

Okay, so for step 1, double check to ensure Residential Gateway Function is disabled: ... emode-cgn3.
Instructions should be similar.
I've had an ISP push a firmware update to a modem/router combo or gateway before, which reset everything. Then I had to enable bridge mode again.

Re: FPL - Calling from Landline ends up in VM

PostPosted: 07/05/2021
by GiJoeBlack
hello @Liptonbrisk

I suppose disabling "Enabled + NAT Helper" did the trick. I can confirm I'm able to call from the line to the FPL # in question to which I was unable and ended up in a VM. I'm going to have few more folks call in to affirm the issue has been fully resolved. I thank you whole heartedly. I will update again. Also thank you for the tip relative to ISP pushing firmware update, I will keep in mind. For now it has been already set to Bridge Mode.

Re: FPL - Calling from Landline ends up in VM

PostPosted: 07/05/2021
by Liptonbrisk
GiJoeBlack wrote:
I suppose disabling "Enabled + NAT Helper" did the trick.

Yes. Just don't use "+NAT Helper".

I thank you whole heartedly.

You're welcome!