New version 15.0.05 not working remotely with 3CX V14SP3 PBX

[eagle2]

3CX client for Android after update to latest version (15.0.05) is not working from Internet with 3CX V14 SP3 PBX. No issue from local WiFi or VPN remotely.

With 3CX tunnel client registers, but not able to make or receive calls.
Same time Windows client or client for iOS works normally remotely or locally.
Firewall checker on PBX passes OK.

Any clue ?

 

[leejor]

Could it be that Client Version 15 is only compatible with PBX version 15?

 

[leejor]

I stand corrected, the Google Play download page states that it is for PBX version 14 or 15.

 

[leejor]

Just installed it on an LG TributeHD (a basic phone), and seems to have no issue, with tunnel on or off over Wifi (different network)

 

[eagle2]

I have a customer complaining for his PBX v.15.0.60903, i.e. SP4 on Windows server -- stopped working after upgrading his Android client 3 days ago with release of V.15.0.05. I don't know which make of GSM phone.
Same behavior on my PBX (version 14 SP3), client for Android is not working on Sony xperia Z3 and on LG Nexus 4, with 3CX tunnel can register, but no calls. Same time client for iOS is working fine, as well as Windows client remotely (with or withoit 3CX tunnel) and CSIP simple on Android is also working. Firewall is OK, I've restarted server and router in front of it.
Reverting back to Android client 14.0.57 is not working any more too (used to work until Dec. 21st).
I will place a ticket to support after Holidays.

 

[leejor]

What, if anything, do you see in the 3CX log after attempting a call? How does the registration look, normal? Is there no audio with both the tunnel on and off? What about the setting on the phone, anything look out of the ordinary? Mine just kept the existing settings, and it is used in conjunction with Version 14 of the PBX.

 

[eagle2]

I can't establish a call with new 3CX client for Android, log attached, I see only registration (extension 277) via 3CX tunnel.
I can register with CSIP simple and make and receive calls (extension 201) through public internet (mobile).
IP deskphone involved (extension 244) in conversation.

Meanwhile the PBX also can't register to callcentric accounts.
Port forwarding is OK (cheched), also firewall checker passes with OK for all ports (5060,9000-9255).

 

[leejor]

Unfortunately, with the latest versions, you can no longer just manually create an account, on the phone, for testing, but what about creating a brand new extension, then send the provisioning file. If that worked, then compare the two accounts.

The only thing that I see in the log, the I would consider a bit odd, are the ports being used, not the normally expected 506X range. Does something on your network change the ports?

By the way, did you rely, like I did, on the previous setting being "moved over" to the new version, or did you send another provisioning file?

 

[leejor]

In version 15, I miss the green dot reminding me that I still have the 3CX phone active, when I may have meant to exit.

 

[eagle2]

I will place a ticket to 3CX Support. The issue is only with 3CX client for Android. Registration is possible only with 3CX tunnel, while other clients like 3CX for Windows or iPhone can register and make calls with or without 3CX tunnel, which is strange. CSIP simple client on Android also registers and make calls. The 3CX client for Android is not able to make or receive calls, even registered. Nothing seen into verbose activity log or in wireshark capture. Strange, but 3CX client works normally if registered in local WiFi or through VPN tunnel by GSM phone.

Nothing special about ports -- I'm using 2 GSM phones for tests over 3G and/or 4G network, everything is default, used to work with previous version of client, may be 14.0.57. However installing now 14.0.57 is resulting in same behavior.

Regarding another issue -- Callcentric accounts, they began to register, after increasing the default re-registration period from 60 to 300 sec., obviously Callcentric rejects too frequent registration attempts.

Meanwhile, I reinstalled 3CX PBX this night and restored backup, but unfortunately this didn't change anything.

 

[leejor]

However installing now 14.0.57 is resulting in same behavior.

So it would appear to not be the client itself but something on the phone has been affected by the first install and remains when the previous version is re-installed, very strange.

Please post the ticket results.

 

[eagle2]

The situation is worse, different GSM phones behave differently with different PBXs, for example Samsung Galaxy Note4 works fine with our PBX (V14 SP3), while other phone like Samsung Galaxy S5, Sony xPeria Z3, LG Nexus 4 -- don't. In the same time the same Sony xPeria Z3 works fine with other PBX (v15 SP4), while others -- Galaxy S5, Nexus 4 -- don't in the same conditions (originating network provider).

I'm still trying to find some logic in misbehavior of 3CX client for Android in different setups. There are cases where everything works fine, but different phones on different PBXs.I'm getting many complains from customers.

 

[eagle2]

The reason for 3CX client issues seems resolved, it is affected by MSS size of TCP packets in router in front of PBX. If you reduce the size to 1300 bytes for larger packets, 3CX client starts to work. This peculiarity also depends on internet providers and make of Android phones -- in some cases combination is working without reducing the MSS size.

 

[leejor]

So, never really having dealt with this before, where was it changed? The device, router, Firewall, or server? It sound like it could affect some user upgrades.

 

[eagle2]

I have several customers complaining about 3CX phone for Android not working, including ourselves. The strange point was one and same Android device, using same internet provider, behaves differently to different PBXs (different internet providers), while different Android devices, using the same internet also behave differently to one and the same PBX (in tests -- ours). In most cases if 3CX client was using landline internet (WiFi) the success rate was better than if Android device (phone) was using mobile internet (3G/4G).

The common point was all PBXs have MikroTik routers in front of them (with SIP ALG switched off in all of the routers). The MSS size is decreased in the Mikrotik router on incoming new TCP connections, which solved the problem. This could be a problem of Mikrotik routers (latest bugfix 6.36.4 firmware, different models), but I guess the 3CX client is sending large packets, which in combination with internet providers overhead or depending on their equipment probably results in damaged packets to 3CX PBX. This suggestion needs confirmation from 3CX development.

I couldn't observe such problems with other routers like Linksys.

Still not in all cases Androd's 3CX client can register to all of the PBXs tested, if 3CX tunnel is not used, despite of permission in extension settings. This could be another issue.

Leejor, I can sent you in PM (or email, if sent me via PM) some wireshark captures, if interested.

 

[eagle2]

MSS issue explained here: http://stevedischer.com/pmtu-and-mss-discovery-issues-resolved-with-mikrotik/
It happens with 3CX client for Android, not with others (Windows, iPhone). May happen with other routers and Internet providers combination.

 

[leejor]

Thanks, i knew that you had a preference for the MikroTik routers and sort of wondered if it had something to do with a setting on them. I have never come across the MSS issue/settings on the routers that I generally use ( Linksys/D-Link with DD-WRT firmware).

 

[eagle2]

I've tested with Linksys with DD-WRT firmware and had no problems also.

However Mikrotik are very popular in Eastern Europe (mostly for price/performance ratio), we are running a cloud cluster with over 100 virtual PBXs, including several 3CX 128 SC installations, based on Cloud-Core Router from MikroTik (CCR-1009) and VMware.

Issue with MSS size happens not only with 3CX clients, but also with some web sites. Interesting point is why it is happening only with Android version and not with Windows or iPhone version.I haven't tested MAC OS version. Something in design or implemetation of 3CX tunnel probably.

 

[Julian Krautwald]

Hey everybody,
we are facing the same problem with the latest Android version and our 3CX behind a Fortigate 90D.
@3cx Support: Can you verify this issue and is there an official solution planed?
Best regards,
Julian