SG200-26P Switch & VOIP Issues

[Justinius]

Hello, I'm a small business owner trying to set up a network at my office with VOIP phone service. I have a little understanding of networks, but am not a professional. We have an SG200-26P switch and have internet access through a cable modem from Charter Business. The cable modem is plugged into one of the ports on the switch. We also have a wireless router plugged into the cable modem. Internet and Wi-fi works fine. I have a dynamic ip address.

I have been unable to get an IP phone to receive an IP address from the switch. Voice VLAN is enabled, so I'm not sure what the problem is. Cisco's marketing touted plug and play VOIP, but it appears it is not so easy!

I spent half a day researching this so far and have not been able to resolve the issue. Any suggestions or hopefully advice from someone with similar issues would be greatly appreciated. Thanks in advance for any help.

[Tom Watts]

Hi Justin, if you factory default the switch and plug the phone in, there should be no problems.

Give it a try, hold the reset for 30 seconds, don't even bother to log in to the unit, just let it takes its natural course and see if the phone receives an IP.

-Tom
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[Justinius]

Tom, thanks for the advice. I tried that this morning and still no luck obtaining an IP address for the phones.

I called Charter Business and spoke briefly with a tech there who told me the problem may be that Charter will only allow three devices to obtain an IP via DHCP and that the problem may lie there. I assume from that I may not have something configured right with my network setup, as all devices may be trying to obtain public IP addresses?

I have my cable modem plugged into one of the ports on the switch. I have a wireless router (non-Cisco) plugged into the cable modem directly. The wireless router is not plugged directly into a port on the switch. Could this setup be causing the problem?

Thanks so much.

[Tom Watts · Accepted solution]

The modem needs to be connected in to an "internet" or WAN port of the router. The modem should not be plugged in to the switch at all.

Internet -> Modem -> Router -> Switch -> Phones/Computers

-Tom
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[Justinius]

Tom, I set it up as you suggested and it worked! I got two VOIP phones up and running and all is well. Thanks so much for your help.