DPNSS and VoIP
For a protocol that began life in the 1980s, DPNSS is natively a long way from VoIP. However, many of the hybrid VoIP PBXs available from manufacturers worldwide provide on-board DPNSS trunk cards. Where they do not, a protocol converter is necessary. Commercially available equipment offers the ability to convert from DPNSS to Q.Sig. Note that it is also possible to tunnel DPNSS and its associated PCM (G711) over an IP network. This can be point to point where the IP network carries packetised voice N x 64 Kbs speech and a separate IP signalling channel to carry the notional 64 Kbs of DPNSS signalling. A more sophisticated solution uses intelligence on the edge of the IP network to route voice to the correct node. This is a Voice VPN. Note that this should not be confused with the pre-VOIP 'Voice VPN' deployed by routing calls intelligently in a TDM switching platform, often Nortel DMS100 and customers PBX nodes.
Read more about this topic: Digital Private Network Signalling System