HTTP ERROR:601 for M2M sims

Hi all
As iam facing a problem that Airtel M2M SIMs getting network error 601 while sending data ,as gprs is getting activated and my device is assigning IP address also, so what is the problem?
can any body suggest…
As it was very clear with old airtel sim

What you are telling is that you are using the exact same system, same software and hardware, that works ok but if you just change the sim, it does not work?