Why does the native SIP stack included in Android 2.3 does not work over 3g?

I was wondering why does the native SIP stack included in the Android framework(since 2.3) does not work over 3g?

Could it have something to do with any laws开发者_开发百科 or restrictions google may have with his partners?

And furthermore, does anybody know if there is any plans to remove that restriction ?

Thx

In GingerBread, SipManager is set to work only on wifi.

`<bool name="config_sip_wifi_only">true</bool>`

But from 4.0 onwards, this config has been changed to false

So Ideally native sip stack should work on 3G from Ice Cream Sandwich onwards.

But again if the phone is sold by a service provider, then this might have been disabled. So phones sold unlocked may have this intact.

To check whether Sip over 3G is supported you can use the api

   SipManager.isSipWifiOnly(mContext);