Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17


How do I enable Cisco IP Phones in remote office?

Posted on 2010-11-18
Medium Priority
Last Modified: 2012-05-10
I have two Cisco SPA504g IP Phones in my remote office across town that need to connect to the UC520 in my main office. I have a SonicWall TZ180 and a couple PCs in my remote office.

In my main office I have an ASA5505 that provides a site-to-site VPN from one of my vendors. An application on my server requires that particular VPN to connect to my vendor. My server provides DHCP and DNS to my PCs, assigning the ASA5505's address as the gateway. My UC520 provides DHCP to my IP Phones, they are on a different subnet than my PCs. The UC520 is behind the ASA5505, does not run firewall, and connects to my POTS phone lines. The PCs are fine, the IP phones in the main office are fine, all works great.

Can my remote phones connect across the internet to my UC520 in my main office?
Question by:squeeky_clean
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
LVL 31

Expert Comment

ID: 34169481
If your VPN is abstracted away from the physical devices on the network - e.g. if your router is responsible for connecting, authenticating and sending data over the internet via VPN to your other location and the rest of your network doesn't need to worry about it, then yes. The phones should just be able to connect just like any other phone in the local office.

If you need any form of "client software" to initate the VPN connection beforehand - e.g. you need to run a VPN client program on your desktops first - then no, the cisco phones likely won't support initiating that kind of connection. (it's possible they do support one form of VPN or another, but I'd imagine it would be a cisco proprietary vpn system, I'd be willing to put more money on that it won't work)

If your phones can't go throughg VPN, perhaps you can connect to your other location directly by it's external IP address, and forward the appropriate SIP ports for your phones on your router?

Expert Comment

ID: 34169737
My recommendation is put in either an ASA or a Cisco 88x router at your second location. Configure a VPN back to the ASA at your office with the UC520. Make sure you enable the VPN to access your voice subnet.
Make sure the VPN is working properly, ie. you can ping all subnets etc. then configure the DHCP server in the remote office to provide a tftp server and point it to the IP of the UC520.
It should all work once you have done that.

Assisted Solution

mark_06 earned 1000 total points
ID: 34169744
Configure a VPN back to the ASA at your office with the UC520

What I mean is configure a VPN to the ASA - ignore my mention of the UC520 in that line.
LVL 33

Accepted Solution

MikeKane earned 1000 total points
ID: 34173928
You would need a VPN as indicated.  

The phones at the remote office would need to be given the DHCP option 150 from the DHCP server there or they would need a static IP assigned to them with the TFTP server IP set as well.  

I've done this many times with 79XX model phones and Cisco UCM.

Are your phones running SIP or SCCP?    

LVL 35

Expert Comment

by:Ernie Beek
ID: 36984618
This question has been classified as abandoned and is closed as part of the Cleanup Program. See the recommendation for more details.

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Use of TCL script on Cisco devices:  - create file and merge it with running configuration to apply configuration changes
This article explains the fundamentals of industrial networking which ultimately is the backbone network which is providing communications for process devices like robots and other not so interesting stuff.
As a trusted technology advisor to your customers you are likely getting the daily question of, ‘should I put this in the cloud?’ As customer demands for cloud services increases, companies will see a shift from traditional buying patterns to new…
Both in life and business – not all partnerships are created equal. Spend 30 short minutes with us to learn:   • Key questions to ask when considering a partnership to accelerate your business into the cloud • Pitfalls and mistakes other partners…

722 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question