SMS center  by itself is a software  on a high spec server but it can be a regular box. its consults HLR and VLR (both are database) for recipient info and communicates with MSC for delivery of the msg. note that MSC here do need a specialized HW.

SMSC obviously should also support SS7, IP and other sms  protocols

with Kannel you don't seems to need specialized hw other than a high spec server, I guess if you do not have connection with smsc of your operator, Kannel will also provides that (I was doing some trial with Kannel over a year ago) and if that's the case the center number should be places on the SIM card as an alternative to subscribers default operator smsc#

First of all accept my apologize that I don’t have info about the hardware  part but in case of software  I should say that there is a server (mostly equipped with SMPP Protocol) dealing with hardwares and telecom switches sending SMS. All mobile operators has this facility to provide you with the access to this message server through SMPP protocol,But the case is that mobile Operators just deal with wholesalers to provide them with this access. In Iran there are 3 companies having this access to “Hamrahe Aval” since 3 year ago and there is a running tender for more companies.

ur answer is "tambur".search in sourceforge

- Smppapi(smppapi.sourceforge.net) or jsmpp or smppsim API to connect to SMSC via SMPP. And an account from a company  SMPP gateway provider for getting connection details to connect/bind to SMSC like host, port, system ID, password.

- For using http just an account from a HTTP gateway provider.(it dosn't need any opensource or hardware  it works as a URL to Send/Receive a SMS)

- GSM Modem and SMSLib.jar to connect to SMSC via GSM.

If you are looking for a Java based SMSC that is also part of a telco middleware platform, take a look at the Mobicents family of projects:
http://code.google.com/p/smscgateway/
http://telestax.com/open-source/

Hi Heru Chalthoum,
In your post you mentioned if Kannel does not have connection to operator SMSC we can put Kannel mobile number as SMSC number in SIM card. I'm trying to do that and can you guide me on how to do it?

What I'm trying to do is replace the SMSC number on my SIM card/phone and send all text messages via Kannel SMSC.

Thanks,
Jacob