Newbie : How to call on cellular networks

Hello everyone. I am new to the forum as well as telephony, so apologies for this very basic question.

I started off with Asterisk: The Definitive guide, which is amazing and I got my SIP connection ready with softphone :smile:
Moving forward I want to establish a connection with a hard-phone on a cellular network. I am getting terribly confused after reading these articles :

  1. - This says I need to install Telephony cards into my laptop and interface with a landline phone I am having. The I need to configure DAHDI on the laptop.
  2. - This link says I need to register for a DID provider and configure an SIP trunk on my system…I did not get what this meant.
  3. Again not sure what it does
  4. In the support chat, I was told to look for GSM gateway.

What hardware do I actually need ? Currently I just need to call from my softphone to mobile phone (in an easy way), I don’t need to receive calls. Is there any other option if I dont have to buy hardware - any organization offers any paid service for this ?

PS : I am from India ;any zone-specific help will be appreciated:)

Thanks in anticipation !

1, 2 or 4. For most people 3 is not an option as it will require a radio transmitting licence in most or all countries, and you will only be able to connect to cell phones within radio ranage and set up for your private cellular network.

Option 1 is the standard direct access to the PSTN method. Option 2 is the standard method of accessing the PSTN via SIP, and requires an internet connection, but no phone line. Both of these eventually connect to the cellular networm the same way as you would from any normal landline phone.

Note DID is a misnomer, and simply means that they forward a PSTN phone number to you via SIP.

Option 4 means using what is basically a cellular phone without a user interface, and directly connects you to a cellular network; it will have its own SIM.

Option 2 is probably easiest for newbies.

Why do you consider connecting to a cellular network to be any different from connecting to the PSTN?

Thanks David !

Actually, I have a doubt on this in terms of basic concepts. When I read about PSTNs, I often get terms like VoIP Provider and non-VoIP providers (which I guessed are the cellular networks) - this made me think there are 2 categories of PSTN ! Can someone please help me get this ?

Apart from this, can you please elaborate on option 2 - can I really proceed on this without installing hardware of any sort ? Is it good for independent developers like me to start with (in terms of cost) ?

PSTN = Public Switched Telephone Network. Whether or not cellular networks are part of it is questionable. Normally the PSTN means someone who will provide wires are fibres to your premises, e.g the wires to a home telephone. These wires allow you connect equipment, e.g. a domestic phone, or complex PABX, and to dial numbers on the PSTN and cellular networks anywhere in the world. They are are standard telephone service.

The type 2 option refers to a company who has a type 1 connection to the PSTN and resells that access. Some may even use Asterisk to do this. There are many of these and you need not use one in the same country, however some countries impose restrictions on VoIP traffic.

You really need to do more background reading. Possibly start with the book at

Thank you David for all the help… I will read more on this.