Call transfer to cell phone, uses two lines?

Hi all,

Please help me understand this… So I have a ring group set up in that a call will be forwarded to my cell phone. So an incoming call comes over the SIP trunk which is using one channel. Asterisk/freepbx opens up another outgoing SIP channel to forward the call to my cell phone.

Once the incoming call is forwarded and accepted by the cell phone, I am now getting charged twice by my voip provider for the call (once for incoming and once for outgoing). Once the call is transferred to the cell, is there any way that the freepbx can be removed from the picture, or does freepbx need to be present to maintain the state of the call and keep the channels open?

thx for any input!!

This is normal behaviour for any PBX as far as I know as the PBX just acts as the “join” for the two calls.