AsteriskC2D and AsteriskC2DPro are identical, with just AsteriskC2D being limited in the number of configurations which can be stored.
With AsteriskC2D you are no longer constrained by where your deskphones are. You can make and receive calls via your iPhone over the GSM network. The voice part of the call is carried by the GSM network so you always get the best voice quality.
Note your PBX will be billed for both the outbound call and the GSM call to your mobile, however in most calling plans this GSM call cost is very small.
|Native iPhone Application||YES||YES|
|Secure Connections (SSL)||YES||YES|
|Number of Configurations||2||Unlimited|
|Support for other PBX systems||YES||YES|
|VoIP Voice Call Handling||NO Voice carried via GSM Network|