Equipment (Modems,Gateways)
Modems, Gateways, and Networking Devices
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Visitor

Cisco DPC3941b replaced SMC and now 8x8 VoIP phones cannot connect

Yesterday Comcast came in to replace a failing SMC box with a Cisco DPC3941b.  Our 8x8 VoIP phones have been working well for about 5 years with the SMC...now they do not.  Internet is OK.

 

Over most of the past 24 hours have been searching and reading various forums like this one and see no solutions.  Spent over an hour with 8x8 support, and ran their network analysis tool which came back with all green checkmarks for about a dozen aspects of required connectivity.  We rebooted the Polycom IP335 phones this morning and the all still come back with "URL call is disabled".

 

I see no QoS settings, and research indicates that SIP-ALG is supposedly disabled by default on these boxes, even though there's no indication for this feature.  SIP-ALG definitely needs to be disabled.  I've opened port 5060 in the Port Triggering section.

 

Often came across the suggestion to have this box put into bridge mode and buy another router for the LAN, but unfortunately I'm away for 2 weeks and have been doing all I can remotely via one of the PC's.

 

There are 7 people without office phones they desperately need (plus no fax now).

 

ANY help is welcome, as long as it does not involve bridge-mode configuration.

 

-CJH

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Visitor

Re: Cisco DPC3941b replaced SMC and now 8x8 VoIP phones cannot connect

OK, just FYI...Comcast is bringing a new SMC box out this afternoon.

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Official Employee

Re: Cisco DPC3941b replaced SMC and now 8x8 VoIP phones cannot connect

Hi Chris, I just wanted to check in and see how things went today. Let us know when you get a chance.

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Official Employee

Re: Cisco DPC3941b replaced SMC and now 8x8 VoIP phones cannot connect

Hi Chris, I just wanted to check in and see how things went today. Let us know when you get a chance.

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Visitor

Re: Cisco DPC3941b replaced SMC and now 8x8 VoIP phones cannot connect

Problem solved!  The 10-year-old Cisco switch decided to give out upon rebooting.  Comcast tech remotely put the new Comcast/Cisco gateway/router into 'passthru' mode and asked that anything between the Comcast box and the client devices be rebooted.  The only thing was an aging Cisco switch.

 

Comcast techs brought in a more VoIP compatible SMC gateway/router that same afternoon...much to our surprise and relief.  But our Cisco POE switch had failed.  Bad timing.  A new POE switch was purchased and installed the next morning and all is well now.  We'll never know if the passthru mode would have worked with the VoIP phones.

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New Member

Re: Cisco DPC3941b replaced SMC and now 8x8 VoIP phones cannot connect

Hi, we are also having problems with the Cisco DPC3941b and VoIP. 

 

What model of SMC modem did they bring out? 

 

And do you think it would handle 150mbps?

 

Thanks!

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Official Employee

Re: Cisco DPC3941b replaced SMC and now 8x8 VoIP phones cannot connect

Hi there, we are sorry for our delayed response and we do appreciate you taking the time to reach out to the Digital Care Team here through the forums. I know how frustrating this must be for you and you have reached the right team to help with your service concerns. Can you please send us a private message with your name, the full address, and phone/account number? 

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