Calling toll free numbers for free (the SIP way)

Of course calling a toll free number should be free.  But what if you have to pay to make any call, say, on your cell phone (you're using minutes), in a hotel, or overseas (yes, you can call US toll free numbers from overseas, but you still have to pay the going rate for calls to the US).  There are many companies that offer toll free call origination over SIP, no registration or contract required. 

This can be setup in a corporate PBX, or even straight from a client on your laptop.

Here's an example.  Using SJPhone you can place calls to SIP URIs (Uniform Resource Identifier).  SIP is a peer-to-peer protocol, meaning, your SIP client can send SIP messages to another SIP client without having to register or authenticate if the other side doesn't require such things.  Generally, this is an uncommon situation.  However, in this case, some companies are providing this service for free, there is no need to setup an account.

In this case, we are using Denetron.  In order to place a call, in the address bar of the phone, put the following:
sip:tollfreenumber@sip.denetron.com

The toll free number for this service must be in the 11-digit format (1-800, 1-888, etc).

This is what the client will look like

 
The client should be in the PC to PC (SIP) mode or profile.

This would be useful if you are overseas and trying to reach a US toll free number.  You can now do it for free.  Or, if you are in a place where your cell phone doesn't work, but you have a network connection. 

A few services I've tried so far:

Denetron: sip:1800NXXXXXX@sip.denetron.com
IdeaSIP : sip:800NXXXXXX@proxy.ideasip.com
TollFreeGateway.com: sip:800NXXXXXX@sip.tollfreegateway.com
TollFreeTollFree.com: sip:800NXXXXXX@tollfreetollfree.com


In these examples, '800' is used to represent all NPAs for toll free calls, including 800,888, 866, 877....

Other services I haven't yet tried:
Call with us: sip: 1800NXXXXXX@tf.callwithus.com