To purchase DID/Tollfree Numbers, first you need to login to your account and then follow following steps.
1. Go to "DID Purchase" Page:
2. Select your origination country from drop down menu, Numbers beside country name shows how many DID/TFN is available for that country.
3. List will come up for all available DID/TFNs, you can see pricing, incoming calls price, number of channels allowed on DIDs/TFNs and billing increment. You can click on "Purchase" button right next to DID/TFNs to but that number.
Once you have purchased the number it will show up in DIDs page from where you can add/edit your Origination IP.