Existing Head Office Panasonic VOIP system vs. Site Offices

Hi Everyone,

I am still a newbie in the VOIP industry, and i am pursuing an idea that i have, i am not sure if it is applicable or not though, perhaps you experts can better assist me.


In our Head office, we have a panasonic IP PBX system, connected with 2 external phone lines. We have a DSL internet connection with dynamic IP address.

And then, we have our construction site offices, let us say 1 site office for now. We have an internet connection at this site office using the 3G routers which also has dynamic IP address.

What i want to do is the following:

Install 1 IP phone set in this site office, which via the 3G router can connect to our head office VOIP PBX, so we can reach this site office as an extension. Also this site office can access our phone lines to make external calls.

Of course, both our head office and site office modem routers have dynamic dns capabilities.

So what do you think, is my idea do-able? what kind of hardware/software do we need from asterisk or digium in order to achieve this?

Kindly advise,


If you can set up a VPN between the two sites, it is doable.

Alternatively, but more difficult to secure, if the IP addresses, although dynamic, do not change, it is doable.

If you have the sort of ISP that deliberately changes IP addresses at regular intervals, you may have to restart everything when this happens.

Support questions should go in a forum with Support in its name!

OOPS! I overlooked the 3G router.

With 3g you have the bandwidth but the latency is just too much. we do have customers with phones connected to 3g routers but quality isnt great.

Hi Guys and thanks a lot for your responses.

If i am to do this without VPN, and since the IP is dynamic, i will use Dyndns.org.

What do i need in terms of hardware and software to achieve this?

Even with dynamic DNS, you still need a stable IP address, as Asterisk will only look it up when starting. Quite a few, mainly consumer oriented, ISPs appear to deliberately produce unstable addresses, possibly to discourage the user of servers.

and what if i have VPN ?

our head office has a firewall which includes VPN, but i am not sure about our 3g router on site.

would that solve the issue of dynamic IP ?

It would push the problem of dynamic IP onto the VPN software. It would be desirable anyway, because it would allow you to firewall out the rest of the world from the VoIP system


so what do i need in order to achieve this solution?

You asked on an Asterisk forum, but on re-reading, it is not clear that you need Asterisk.

Apart, possibly, from something more VoIP friendly than a 3G router, and the phone itself, you may not need any additional hardware, but that depends on the capabilities of the existing PABX.

well i do need asterisk hardware and a digium phone set for the site office don’t i?

well i do need asterisk hardware and a digium phone set for the site office don’t i?

depends on how many extensions you are putting there. if its one then no you dont just put in a voip extension from your panasonic box

cool thanks

so any idea where i can get more information about setting up this vpn ?