SMS capacity not reached

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Tim Schneider
New member
Username: Fyjham

Post Number: 1
Registered: 12-2008
Posted on Thursday, December 11, 2008 - 11:56 pm:   


We've recently increased the capacity of our NowSMS licence from 2 messages per second to 5 messages per second but we do not seem to be able to max out our capacity. We have submitted 19000 binary SMS messages spread over 90 minutes through the web interface so far today and only 10000 have sent (3.6 per second requested, 1.8 per second sent), the rest are in the NowSMS queue so we're fairly certain the bottleneck is not in the delivery to NowSMS.

The server hosting NowSMS is only running at roughly 12% RAM 20-50% CPU usage, which makes us think the our server's hardware is capable of a higher capacity.

We're currently raising a support call with our provider to see if their SMPP server is at it's capacity, is there anything further we need to do to activate the new license (We have loaded it through the UI and it says it's valid for 5 messages per second then restarted the service) or anywhere we could use to try to determine exactly what is causing the bottleneck (Our current theories are that either we're maxing out something on our servers that's slowing the delivery, the new license not processed properly or the SMPP at it's limit)?
Tim Schneider
New member
Username: Fyjham

Post Number: 2
Registered: 12-2008
Posted on Friday, December 12, 2008 - 12:29 am:   


Another thought crossed our minds, would delivery reciepts be counting as a second message towards our maximum 5 messages per second?

All previous calculations were only including outbound and it just occured to us that the delivery reciepts may be bringing us to the limit of our licence...
Des - NowSMS Support
Board Administrator
Username: Desosms

Post Number: 326
Registered: 08-2008
Posted on Friday, December 12, 2008 - 08:46 pm:   

Hi Tim,

Outbound messages vs. inbound messages are metered separately.

So receipt of inbound messages don't count against outbound message throughput.

There is an issue that delivery receipts can slow down 2-way SMS processing of other received messages ... depending on the NowSMS version. In some versions of NowSMS, the delivery receipts are counted as inbound messages, and the 2-way command processor limits its speed to the license speed.

However ... I should stress, this doesn't effect outbound speed.

Do you have SMPP async mode enabled? This is an "Advanced Setting" for the SMPP connection that is defined under "Properties" of the SMPP connection in NowSMS.

Not all SMS service providers support this ... so you have to watch your error rates after enabling this setting. If you see a lot of retry errors, then go back to disable async mode.

I usually recommend setting the async window size to a value of twice the desired number of messages per second.

If async mode is not supported by the provider, then the only alternative is establishing multiple binds to the provider. (Async mode is preferable.)

When async mode is not enabled, that means that NowSMS will not submit another message until the provider has acknowledged the first message. The speed of the connection is effectively throttled by the speed at which the provider ackowledges submitted messages.

When async mode is enabled, NowSMS doesn't wait for that acknowledgment, instead queueing up multiple messages (up to the window size max) and can achieve faster speeds.

Async mode is faster ... and the preferred solution ... it just isn't supported by all providers, which is why it is not enabled by default.

You might also find this article informative:

NowSMS Support
Tim Schneider
New member
Username: Fyjham

Post Number: 3
Registered: 12-2008
Posted on Sunday, December 14, 2008 - 11:40 pm:   


Thanks for your help. We have managed to reach capacity now.

We tried the async mode and it is supported by our provider but didn't really improve the throughput.

We seem to have gotten the improvement by changing our bind from a tranciever to a transmitter.

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