AASTRA SIP-DECT (Release 1.8)-Installation- and Administration Guide EN - Manual (Page 13)

Installation, Administration and Maintenance
Aastra depl-0900/0.4 Page: 13 (104)
A call from one PP to another that resides on the same RFP will loop back
within the RFP, if no media gateway is involved. So the call will not pass
through to the Local Area Network (LAN). Although the voice packets will not
impact LAN traffic, signal packets will.