PlaySMS + smstools3: How to make multiple modems round-robin

I wanted to know if anyone had set up multiple modems in SMSTools3 and got them to work in a round-robin format. I know that playsms uses SMSC which appears to only be able to point to a single modem.

Thanks in advance for any help on this.

If you add same prefix and point to the same smsc then playSMS will randomize which smsc be used for delivery

Not round robin but will usually get equal traffic on each modem


Hi Anton,
Wanted to say thanks for building this software! It is very nice.

I am not sure I understand what you mean by 'prefix’
In the SMS tools config file I will need to set up the second modem, e.g. GSM2 and on a different ttyUSB
so the SMSC will need to be different?

in current release you can set a modem in smstools3 to an smsc in playSMS, and then playSMS can route outgoing SMS by prefix to certain smsc (thus to your modem)

if you route the same prefix (from playSMS, in route outgoing sms) to different smsc then playSMS will pick which smsc randomly

of course first of all you must configure both smstools3 and playSMS correctly, try to read this:


Aha, the dialing prefix. Got it! Thanks.

DO I need to set up separate queues (outgoing)?

Yes, you need to separate modems by queue

here is the example for 2 modems with each modem1 and modem2 queue:


OK I did this, however with smstools3 it will work with a single queue…

What exactly you have done?


When I first tried multiple modems I did not specify queues in smstools and then in playsms I specified the same queue for both SMSCs. Seemed to work. But I changed it to have separate queues just to avoid unexpected behavior.

Hi Scott - Anton. I already configure separate modems queue. Could any of you guide me where the prefix is set? I have to configure 2 SMSC too?

btw: smstools is handling several modem automatically. simply use one smsc for smstools in playsms, the rest can be done smstools internally.
@vegacrc: prefix is set in route outgoing sms

@andre Right now I have set up three modems working without problem individually. And I set Playsms 3 different SMSC.
If I understand correctly, I should only set one SMSC in Playsms and tools will make balancing sms sending? Mixing shipments between 3 modems.

I also set up route outgoing?

i didn’t say you have to, but it is possible and from my point of view easier.
outgoing route is not needed necessarily if everything goes out through that one and only smsc. I have 1 smsc (smstools), but use the outgoing route to only allow specific numbers (only mobile numbers).


Thank you Andre. I’ll try your suggestion.


Just as an aside, if you do this and don’t distinguish your SMSC’s you may have trouble tracking down issues if one modem stops working.

from playSMS point of view you are right, but you can narrow down the issue on playsms side, where you see which gateway was or is failing. but usually it is no problem if one gateway fails, then the other gateway will process the sms.


That is a very good point and I will evaluate using this configuration. Thanks Andre.