Best Router/Switch setup for Comcast Business

So we have Comcast business 50up/15down using FreePBX. We have the default all in one Wireless Router DPC3939B Model, in Bridge Mode going to a TP-Link 24-Port Gigabit (TL-SG1024) and the phones go through a separate POE switch (WS-POE-12-48v60w). We have been experiencing phone call quality issues, with Packet drops. Our SIP provider can see the dropped packets, but Comcast sees everything running ok. I seem to think it may be either the Comcast Modem or the TP-Link switch. Are there any recommendations on maybe a different switch that has Gigabit and has been proven to work with FreePBX?

So, it sounds to me like you’re thinking that the problem is your hardware, even though Comcast says the packets are all making it to them but (further upstream) your provider says they aren’t.

Since you know (it’s Comcast, so I understand their level of reliability) that the problem exists between Comcast and your provider, I’d suggest that you submit a ticket with Comcast and let them know that their technicians are telling you it’s a problem with the Comcast network. If nothing else, it should be worth the fun of watching Comcast local fight with Comcast national for a few minutes.

After that, I’d suggest replacing the 24-port switch. I’ve had problems with these a couple of times - they work fine for a given period and then start to do flakey things that always end up looking like problem with other equipment.

For switches: I tend to like Netgear Smart Managed switches (
The GS728TPP is what I tend to keep readily in stock.
Setting up VLANs for your phones works pretty easy with Auto Voice VLAN there are also some QoS features.
Lifetime warranty and lifetime next business day replacement if one does happen to flake out.

For routers: It really depends on the client. I tend to use Sonicwall for most, but I’ve also used Ubiquti Unifi SG and Cisco ASAs for others.

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I have a GS748TPS that I acquired. Are these similar to the GS728TPP?

That switch is End of Life, but you might give it a shot. It’s basically a 48-Port PoE Smart Managed Switch w/ stacking capabilities. Just make sure the firmware is up to date.

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Ahh no wonder. A friend of mine gave it to me. Said it had been sitting in their workplace for a while new in box. Explains why. Haha. Thank you.

Im surprised you were able to get calls working at all with that Modem from Comcast. It is known to enable SIP ALG without anyway to disable it.

I discovered this after 12+ hours straight of troubleshooting a new install one time with Comcast support saying its all fine and me trying a new router and troubleshooting FreePBX with my SIP provider

I would say use your own modem, but in that situation with a Business connection and static IPs,they required us to use their modem. After I requested they install a different modem they came and installed an old beat up SMC model which was the last one they had because they were converting everything to that Cisco model.

The SMC model worked right away and the problem was resolved.

See here also

  1. you can’t use your own modem with comcast business
  2. you can disable sip alg on the comcast business modem
  3. get yourself a good session border controller that does traffic shaping - we use edgemarc’s -
  4. turn off wireless on the comcast modem. if you need/want wireless install something else but make sure it is connected to the lan side of the edgemarc. there are any number of decent wireless access points out there - ubiquity makes some good moderately priced waps
  5. the switch you have is fine - unless your pc’s are all maxing out your lan (highly unlikely)
  1. Correct
  2. You can’t* disable ALG on this specific modem, and its amazing why ALG runs on a device that is supposed to be in “modem mode” anyways and not router mode. I discovered this was possible because the “modem mode” isnt a modem at all, it creates a layer 3 bridge with SIP ALG enabled and no way to disable. There is no setting on the modem to disable it.
  3. Nice to have and may fix choppy audio with QoS but ive found it not necessary in majority of installs with fast internet connection, deffinitely nice to have tho
  4. 100% agree Their equipment is awful just use it as a modem only
  5. Agree also, its very unlikely to be a switch problem but not impossible

Thanks all for the reply. I talked to Comcast Business and they said I could use my own router as long as I was not paying for a static IP. I purchased an Arris Surfboard so I can do some testing with a different modem, as the Static is not too much of a huge deal. I have already set them up with the Ubiquity Pro for 2.5 and 5Ghz wireless so we are ok there. I am going to test a few different configurations with the new router/modem and then existing comcast modem with a managed switch as well.

i use the arris surfboard at home with Comcast. it works pretty well. i also run an edgemarc 4700 behind it to ensure that streaming video does not impact voice quality.