This is a small implementation of VoIP, especially suitable for a Home or Home/Office scenario.

It would be either a separate telephone connecting to a VSP, or an existing telephone connecting to an adapter, which connects to the original telephone line and to a VSP.

With this type of setup, any/all of the following can be achieved:

• Cost-effective outgoing calls: Most VSPs charge around 10 cents per call, Australia-wide;
• Free calls within VSP: Many VSPs do not charge for calls between their telephone numbers;
• Separate incoming telephone number: Which might be within your local call area or might be assigned from a different exchange ares (such as a capital city);
• Free Voicemail: Most VSPs provide free voicemail on their numbers, and can forward the voicemail by email;
• Free Caller-ID: Most VSPs also provide free Caller ID;
• Call Diversion and Call Waiting: Usually provided free, typically the VSPs outgoing call charge for diverted calls;
• Single Telephone: Existing PSTN service and the VoIP service can be answered from the same telephone, and outgoing calls can be made on either number; Naturally only one person can be using the telephone at any time;
• Separate Telephones: Existing PSTN service and VoIP service can be on separate telephones, and both can be used at the same time.

This can be cheapest of all implementations, but it also tends to be the most limited. Expansion often means duplicating everything, including all setup and ongoing costs.

Costs:

Setup costs can vary significantly, from approx $60 to $200+, depending on telephone/s and any adapters purchased.

Ongoing costs are typically around $10 per month, plus calls.