The PhoneBoy Blog


Simplifying Telecom, Mobile Phones, Gadgets, and More!

IPKall and Outgoing-only Service Providers

IPKall, as I have written previously, provides +1 360 PSTN telephone numbers to point to any arbitrary SIP URL. This allows you to map a PSTN number to a Free World Dialup or SIPphone account. It also allows you to an Asterisk server or a standalone SIP device such as a Sipura SPA-2000.

Today, I discovered that it was possible to combine IPKall with an outbound-only service provider, such as Terracall, and come up with a more-or-less fully functional bi-directional VoIP service for the cost of outgoing calls only, including voicemail! I will explain, briefly, how this works.

Configure your device as you normally would. In this case, I did it with a SPA-3000, but you could probably do it with anything. I set three settings on the SPA-3000:

Register: No
Make Call Without Reg: Yes
Receive Call Without Reg: Yes

Basically, it means “don’t register” (for a truly outbound-only service, registering is not necessary), allow the device to make a call without registering (usually, this isn’t allowed), and allow the device to receive a call without registering (again, usually not allowed).

The next trick is: figuring out your SIP URL. There’s three parts: the username, the hostname, and the SIP port.

The username is easy: use the same username as you use to authenticate with your provider. The SIP port should be listed in the configuration of your device.

The hostname is a bit trickier. My SPA-3000 is behind a router, but this router has a static IP with a static DNS name for that IP. You might have to use something like Dynamic DNS to get a hostname. You can do it with an IP only (no DNS name), but it should be static.

As an example, let’s assume my SIP URL is [email protected]:5060. IPKall asks for the SIP Phone Number (which will be “sipuser”) and the SIP Proxy (which will be host.example.com:5060).

Of course, for this all to work, your Internet router will need to have port forwarding configured for your SIP port as well as the range of RTP ports used by your device. You should also use STUN or otherwise enable the various NAT parameters in your device as well.


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