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Contributor

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3 Messages

Tue, Jan 21, 2014 12:04 AM

3g Microcell and Charter Cable

Hi

 

I have had a 3g microcell for over a year.  Suddenly this week the 3g light starts flashing and phones no longer connect.  I have:

 

deavtivate and reactivated too many times to count

factory reset my modem, router, microcell

replaced microcell with new one

opened all ports listed in various posts and att support site

turned cellular data and 3g data off on iphone

used priority set up (modem then 3gMC then router, this is how I am configured now)

 

What ever I try, there is still no connection back to att network.  ATT support says it must be charter cable and charter cable says it is att.  The only port I can not touch is 123 NTP.  I don't know what is hooked up to it, but it is not accessible to me.  However, using the priority config should bypass any port issues...right?

 

Please help.

Responses

acouse

Teacher

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27 Messages

7 years ago

Hi, thanks.  Yes, I certainly understand to keep the setup simple and that the speed tests are just snapshots in time  (I work in the IT field myself).  My setup including the Vonage piece and MCell had always worked just fine in the past, up until 2 months or so ago when suddenly my Internet speeds and voice quality on both VoIP services went down the toilet.

 

Yeah, I had to force MTU to 1492 and I do have DHCP enable to hand out IPs.  There's no setting control for IPSec Passthrough or Fragmented Packets in the router so I can only assume those are not causing the issue.  Both my Netgear N750 router and my SB6141 are less than a year old.

 

I'll have to keep plugging away at this and possibly contact AT&T MCell and/or Charter Support to also get some feedback from them.  Now, if they just had an entire team of Support staff as knowledgeable as you guys! 

 

I'll keep you posted.

Avedis53

Professor

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2.2K Messages

7 years ago

SIP ALG stands for Session Initiated Protocol Application Layer Gateway.  That's a mouthful!  SIP ALG is typically enabled in most routers by default. So what does it do?  It optimizes VOIP traffic that uses SIP.  The problem is that SIP ALG doesn't play well with VOIP applications that don't use SIP and it doesn't play well with NAT.  I could go into the technical aspect of why this is so but I'll leave that to the reader to delve into it if they want to.

 

I'm guessing that the Mcell is not an SIP device and therefore presents issues when used with certain routers that have SIP ALG enabled.  My Netgear 3500L router has SIP ALG enabled but I also have my NAT set to "Open" instead of "Secured".  This option determines how the router deals with inbound traffic. The Secured option provides a secured firewall to protect the PCs on LAN from attacks from the Internet, but it may cause some Internet games, point-to-point applications, or multimedia applications(ie. the Microcell) not to work. The Open option, on the other hand, provides a much less secured firewall, while it allows almost all Internet applications to work. 

 

I haven't messed with these settings since my Mcell works well with them as is.  Since you have a different Netgear router than I do, perhaps the firmware is slightly different and is causing you problems with the Mcell with regards to SIP ALG being enabled.

 

Don't know anything about Vonage hardware so I can't be of any help there.

 

@ Otto - You should tuck this SIP ALG disable trick in the Tech Guide perhaps?

 

 

 

 

 

 

___________________________________________________________

MicroCell Technical Guide by Otto Pylot


I am not an AT&T employee.

OttoPylot

ACE - Expert

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12.6K Messages

7 years ago

Thanks partner. I get so focused on AT&T's VoIP that I forget about other VoIP services and the fact that they may use a different type of connection protocol to move traffic. Sounds like the basic answer to this is don't use the MicroCell if you have Vonage as well because of the requirments that Vonage needs. I don't know if the Apple Extreme Base Stations has SIP ALG or not. I'll have to look into that and see what I can glean from AT&T on the SIP ALG/MicroCell issue as well.

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acouse

Teacher

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27 Messages

7 years ago

I still have my Vonage adapter unplugged and completely out of my set up and still get some outbound garble on the MCell.  It's so strange because with the V-Adapter out of the equation, I get much better speed and VoIP test results with minimal jitter... but like I said, I still get some garble when using the MCell which is behind the router.

 

It's got to be something to do with this Netgear N750 and something to do with how it prioritizes traffic that I can't control via the firmware (I do have the latest release installed).  When I plug the MCell directly into my SB6141, the call quality is bang on.  I would think there would be other people out there who are running an MCell behind an N750 too but I can't seem to find anything out there when Googling it.

 

I'll keep puttering away at this.

acouse

Teacher

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27 Messages

7 years ago

...and by the way Avedis53, I read about setting NAT to Open as well and am very hesitant to comromise security for this.  What I'll do is set it to Open for a short time, do some test calls then set it back to Secure.

 

Some other people are suggesting to disable port scanning too but that's opening a big security hole too.  Again, I'll disable this one for a short time to test then flip it back.

 

I agree...  Otto: maybe add the disable SIP ALG setting suggestion to your MCell documentation as that for sure improved my call quality.

OttoPylot

ACE - Expert

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12.6K Messages

7 years ago

I've asked AT&T about the SIP ALG protocol so we'll see what I can force out of the engineers. If I can't get anything definitive, I just may have to add it as a "possible" interferent and leave it at that.

 

As far as NAT goes, you can't have both devices (router and modem/gateway) performing NAT duties. That is called double NAT and the MicroCell will have definite issues with that. NAT is disabled on my gateway and only my router (AEBS, Apple Extreme Base Station) is performing NAT. If port scanning interrupts the specified port in any way, even for a brief period of time, that could be another source of problems for the MicroCell.

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Avedis53

Professor

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2.2K Messages

7 years ago

I think that's a good idea to test your connection quality with NAT set to open to see if it helps.  Likewise, testing the port scanning disable.   I have a hunch though that neither will improve your outgoing voice quality.

 

Have you tried adding a QOS Priority Rule for your Mcell by MAC address?  Do you have devices connected to your network that could be hogging your upload bandwidth? 

___________________________________________________________

MicroCell Technical Guide by Otto Pylot


I am not an AT&T employee.

Tutor

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5 Messages

7 years ago

I have been on the phone with ATT multiple days and hours, one call lasted 3 hours. Although the tech was very nice and tried everything in terms of suggestions nothing has resolved the issue. I have done this same exercise with Charter.
So yes, we have hard reset, power cyceled EVERYTHING so many times I have lost count. A charter tech has even come to my house and reset the router back to factory settings. AT&T has replaced the microcell, both the old and the new have the same result. And yes this started about 3 weeks ago now. The lights on the microcell are all green, none have ever been red.
The top three are solid green and the bottom is flashing green. The microcell website activation process stops on the third stage trying to establish the GPS location. ATT and myself have deactivated the device and reactivated it multiple times.
Before this outage, NO equipment had been changed. This device has worked fine for the last year without issues.
OttoPylot

ACE - Expert

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12.6K Messages

7 years ago

Where are you located? I know that Charter was going to start rolling out the new network boxes after the initial roll-out in the Dallas-Ft. Worth areas so it's possible that they aren't fixing whatever the problem was until there are reported issues.

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Tutor

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5 Messages

7 years ago

I am in Edwardsville Illinois, close to ST. Louis
OttoPylot

ACE - Expert

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12.6K Messages

7 years ago

Ok. I'll send an email to the Charter Engineer who helped us with the Dallas-Ft. Worth area and see if one, he'll respond to my email and two, if he can help.

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OttoPylot

ACE - Expert

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12.6K Messages

7 years ago

I've attempted to email the Charter engineer at the email he supplied us and it is bouncing back as undelivereable. He may have changed his address for that very reason. You will have to contact Charter support then and see if you can find out if they have been upgrading the network boxes for your region and refer them back to the issues that were corrected in the Dallas-Ft.Worth area for similar problems. If it is due to a Charter hardware upgrade, there is nothing, or very little that AT&T can do. If we can't get it resolved here (it might not be a Charter upgrade issue) then I'd suggest sending a PM to CustomerCare detailing your issue, what you have done to correct it, refer to the previous Charter issue, include your account info and your location.

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OttoPylot

ACE - Expert

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12.6K Messages

7 years ago

@acouse - Concerning the SIP ALG Vonage protocol:

 

SIP ALG will not cause problems with the MicroCell as the MicroCell does not use the SIP protocol. However, in many cases, SIP ALG is implemented poorly and can cause other issues. If you can get your MicroCell to work with SIP ALG turned off, then that's an indication that the SIP ALG is being implemented poorly causing MicroCell traffic disruption. In theory that shouldn't happen but......

 

The fix, if you want/need to use Vonage at the same time is to setup port forwarding on the Vonage V-adapter using the same ports required for the MicroCell: UDP port 123, TCP port 443, UDP port 4500, and UDP port 500.

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Avedis53

Professor

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2.2K Messages

7 years ago

Personally, I wouldn't put the V-adapter ahead of my router for the same reason I won't put the Mcell ahead of my router and that is limited bandwidth and latency.

 

You should be able to plug the V-adapter into your router just like any other LAN device.  I would assign the V-adapter a static IP address in your router and then place that static IP address in your router's DMZ.

 

Try that and see if you can make Vonage calls.

___________________________________________________________

MicroCell Technical Guide by Otto Pylot


I am not an AT&T employee.

OttoPylot

ACE - Expert

 • 

12.6K Messages

7 years ago

That might work as well. I haven't seen the V-adapter so I'm not sure what configuration options there are. I was able to get a hold of one of the MicroCell engineers and that was his suggestion.

 

SIP uses UDP and may be locked into specific ports. It also has difficulties with NAT.

 

 

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