A. General information

Currently, all of the following settings can only be made by the support team!

In certain situations, it makes sense not to carry out voice data via the telephone system but via the local company network - directly from telephone to telephone. For example, this can be interesting for customers with a high call volume within their location (e.g. authorities) and in cases where the Internet connection provided for telephony should be kept to a minimum. For cases like these, there is the option of keeping voice data (RTP) directly within the local network (LAN). The setting, which must be adjusted, is CANREINVITE, which NFON can configure for a location and devices are in turn then assigned to this location. Alternatively, it can also be selected directly in the device setting.

Requirements for and limitations of this function

  • CANREINVITE only works on devices for which no call recording is activated.
  • Telephones of one location must be able to “see” or directly reach each other in an IP-technical sense.
  • Limited support for calls not conducted via the telephone system.
  • SIP ALG (SIP Helper) cannot be active in associated components such as Firewall or router.


If CanReInvite is set to TRUE, the audio of devices of different locations is supposed to connect internally. Every device with active CanReInvite (whether at the same location or not) will try to send the RTP data stream locally. If both devices cannot reach each other by their LAN IP, the audio data stream stops.