PC to Phone service is a great option for people who travel with a computer and want to make low cost domestic and international calls from any location. All you need is an INTERNET connection and you can make calls from any location in the world. A great deal for international travels or
expats living in overseas locations. It is also ideal for students or military personnel. In most cases you can make Free Calls to other people using PC to Phone service from the same service provider. Call quality can be very good but it depends on the quality of the INTERNET connection being used to make the call
If you need calling for your business, you can use conference calling services. Conference calling is a call that is made between a number of parties by way of either applying a phone built for calling out on several lines or by using a meet meќ or conferencing line where the multiple can call in. The idea for conference call is widely used by some businesses throughout the world for the purpose of having virtual meetings, and for that, conferencing equipment is usually built by multiple manufacturers

SS7 signalling is the core signalling/control protocol used within fixed and mobile networks. The SS7 network is both a high speed and high availability network providing the backbone of all telephony networks worldwide. All major networks around the world use SS7 to provide their major services including POTS (Plain Old Telephony Service), Intelligent Networking, LNP (Local Number Portability), 0800, Wireless, SMS and a whole host of other services. The following is a brief overview of the different SS7 architectures.
SS7 (or C7) is the main signalling for PSTN interconnections. How do we interface between a SS7 network and a SIP network?