Hacking a pager (part 1)

I bought this weekend a pager for 2 euros and decided to plug my scope on it to see what could I find out. The case mentions 147.250MHz, and "RTT/SMF/X205", unfortunately this didn't help much!

I plug my scope on the digital output of the receiver and I noticed a burst of serial data every 1 second exactly.



I zoomed in to see how this bursts look like and this is what I got:



BTW the blue channel is hooked to a pin that goes low every time there is serial data coming in the red channel.

The next think I noted, is that once in a while I get loooong bursts of serial data that last for 4 seconds



Any idea what protocol this could be? It doesn't look like FLEX or POGSAC...

Thanks everyone for reading, any info is welcome!