Hi Steve,

SMS messages are being send synchronous, so one by one. And I don't immediately find some specs back in the manual of the Tango device, but DataMiner has a queue to buffer these messages. In other words, there is no real limitation on how many messages you can send simultaneous, but it might take some time to get them processed by the mobile gateway.

You can view this queue 'SMS stack' in DataMiner Cube > System Center > Mobile Gateway > Status tab page.

Bert