Our company successfully uses smsd with several GSM modems ( with COM interface ).

I am interesting , is it possible for smsd to operate with so called GSM gateways , single hardware modules that include several GSM channels and SIM cards.

The question is actual for us , because we forsee situation when number of modems will increase , say , up to 20 - 40. In this case , it would be difficult to maintain them all and protecti all those devices through a UPS.

One of devices I mentioned is "2N® BlueTower Multichannel GSM Gateway"
( http://www.2n.cz/products/gsm_gateways/isdn_pri_gsm_gateways/bluetower_gsm_gateway.html )

Thank you in advance.

The main purpose of those kind of devices is much more than just being an SMS gateway. Switching of SIM cards cannot be used because it's not supported by the smstools. Each GSM module should have it's own and independent serial interface, which may be expensive, or impossible with some devices.

IP based communication would be much better to use with those devices, but it requires lot of enhancements to the smstools code.

With about 40 modems, some serial port server could be used, assuming that it has a driver to create virtual serial ports. Otherwise IP based communication will be needed and it means a changes to the code.

With power supplies, isn't some cheap multi-socket extension chord enough?

Thank you , keke !

I just wanted to know , how smsd users exploit a great number of modems.
Whether alternative hardware exists compartible with smsd allowing to place all sims in one place.

I agree with you about multi-socket extension chord.

PS
From hardware documentation (for device mentioned above in this thread) I was unable to understand , what is their communication protocol to send / reveive sms.

After investigation of device documentation I have found that it is possible to control it via Telnet over IP.

My question : whether smsd can use such an interface?
( may be with aid of additional components like Interceptty ? )

Below are some commands supported by the device:

AT^SR=ch,ix
request to read SMS
AT^SD=ch,ix
request to delete SMS
AT^SM=ch,len,pdu,csum
request to send SMS

I have tested interceptty couple of years ago with a modem connection and it worked well. For telnet usage I think that smsd could be enhanced to use sockets instead of using additional components which require setup and maintaining.

The command set for handling messages is not standard in 2N® BlueTower. The smsd should be changed anyway to handle different syntax and different responses.

If you have (or are going to have) such a device, perhaps I could make the necessary changes to the program. But it would be a commercial work.

Have you noticed that there is a 2N® SMS Server application available too? Probably it is useful for your purposes.

Thanks , keke

Their SMS Server is not appropriate solution for us because it is intended to accept requests from within LAN. The same is for sms replies.
This is not the case for us.

Now I am waiting for response of 2N support team to clarify one important question :
whether their Telnet - IP communications can be performed simultaneously for different sims / channels.

Only after positive answer it will be possible to decide : to use the device or not.

I will bear in mind your proposal of course .