# Error sending more than one SMS **URL:** https://forum.sierrawireless.com/t/error-sending-more-than-one-sms/3151 **Category:** Open AT **Created:** [April 22, 2009, 3:34pm UTC](https://forum.sierrawireless.com/t/error-sending-more-than-one-sms/3151 "2009-04-22T15:34:46Z") **Posts on this page:** 1 **Showing post:** 14
### Author: ![awneil](https://avatars.discourse-cdn.com/v4/letter/a/49beb7/32.png) [@awneil](https://forum.sierrawireless.com/u/awneil) #### Post date: [April 8, 2013, 10:58am UTC](https://forum.sierrawireless.com/t/error-sending-more-than-one-sms/3151/14 "2013-04-08T10:58:03Z")
> [@GaneshPawate](#): > > the confusing bit for me is wait until you have received both… > . where shld i wait (i think in cntrol handler)? No! You should certainly not wait in the Control Handler ❗ Think about it: If you put a wait in the Control Handler, then the handler will be “stuck” and the system will not be able to call it again ❗ > [@](#): > > Can you please give me a clue/ idea about waiting state and sending text outside the control handler? You need to understand that Open-AT is an Event-Driven system - see this thread for some materials on Event-Driven systems: > [@Good paper on Event-Driven Programming](https://forum.sierrawireless.com/t/good-paper-on-event-driven-programming/3848/7): > > Discusses Event-Driven programming, and why State Machines are often a very good “fit” for such tasks. Provides an example of the type of mess that’s all too easy to get into by doing Even-Driven programming without State Machines: [embedded.com/design/prototyp … nes-Part-1](http://www.embedded.com/design/prototyping-and-development/4008247/1/A-crash-course-in-UML-state-machines-Part-1) Part 2 looks at extensions provided by UML to the basic State Machine concept --- _[View the full topic](https://forum.sierrawireless.com/t/error-sending-more-than-one-sms/3151)._