Secondary PDP context and Direct tunneling!

LTE dedicated bearers are something similar to secondary PDP contexts from GPRS world.

Direct tunneling is one of the release 7 features which says the user plane path could be directly from RNC to GGSN. This will avoid user plane processing in SGSN.

My question is how many service provider networks have implemented direct tunneling? Also who all have provided the support for activating secondary PDP context? I believe most of the smart phones do have support to activate secondary PDP contexts, but how many are actually doing it?

Could somebody please enlighten me in this regard? If the information is confidential please feel free to email me. I shall not disclose the information anywhere, it is for my personal study. Thanks!