Opensource Billing Solution for Kannel

I want to build a billing system for Kannel - the usage of every user of the Kannel based SMS gateway may be tracked and billed accordingly.

I was wondering, rather than building from scratch, are there any generic openso开发者_高级运维urce billing solutions which may be integrated into Kannel?

It should be easily extendible so I may introduce my own reporting and other interfaces. Also, scalability requirement is high as it needs to process large volumes (maybe thousands of SMS/sec) but billing may not necessarily be in real time.

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I am using playsms and it is a nice web based open source application to utilize kannel and other gatways too. As far as i know it have its own billing module but now sure it is extensible.