Linked by David Adams on Mon 21st Mar 2011 20:14 UTC, submitted by Anonymous
GNU, GPL, Open Source The GNU Project has announced a new project called GNU Free Call, an open source Skype alternative that will offer anonymous VoIP and will use the GNU SIP Witch server as the back end. GNU SIP Witch requires a minimum of system resources so it can be used on cell phones too so it seems the goal is to provide a cross-platform application, the immediate target most probably being Android.
Permalink for comment 467508
To read all comments associated with this story, please click here.
RE[6]: 'Twas about time
by spiderman on Wed 23rd Mar 2011 06:51 UTC in reply to "RE[5]: 'Twas about time"
Member since:

Firstly, you still haven't addressed the firewall/ALG issue with SIP I brought up twice, which still exists without NAT.
I don't have to address all your points. I agree the SIP protocol could be better engineered but I don't get what is the need for a firewall when your voip application has its own IP address.

Secondly, whether you choose to acknowledge it or not, port forwarding does have valid uses outside the scope of mitigating limited number IP addresses under IPv4.
NAT has no use for voip.

One example is load distribution, the gateway router should have the ability to redirect inbound packets to multiple servers. This is an example of something NAT is good at.
load distribution does not make sense for a voip application.

Another example is the ability to use one domain name for multiple services. Domain names (typically) resolve to one IP address, without port forwarding/NAT, you're essentially forcing all daemons for one domain name to reside on a single server. This is a stupid limitation. For example, I may want '' to have HTTP, FTP, SIP, all residing on separate servers. NAT/port forwarding on the gateway is far simpler, more efficient, and more scalable than forcing all protocols to be handled on one server.
domain names don't apply to voip.

Another example is a company moving servers to a new IP/location may want to port forward the requests on the old IP to the new servers' IP.
That is why there are registrars. Just tell your registrar what is your new IP address and you are done.

A similar example is when a server has maintenance downtime, the admin can forward requests at the gateway to an alternate server until the original server is ready. The port forwarding switch is instantaneous.
And the registrar request to change your IP is also instantaneous.

I definitely understand the motivation for IPv6 and eliminating the dependence on NAT. However, it seems you've overstated your case that it is never useful.

No, I stand by my claim. NAT is useless for VoIP. You are digressing because you want to prove that SIP is a bad protocol. I don't disagree with you but IPv6 and VoIP is a perfect match. The QoS of IPv6 is a nice feature. The single biggest problem with VoIP is IPv4. IPv4 is a nightmare. Give me IPv6 and I can cope with the SIP protocol quite easily.

Reply Parent Score: 2