Frequently Asked Questions - Network Equipment

Question 1: What are VoIP Gateways?

Answer: 

VoIP Gateways are devices that take analog voice signals and convert them to IP for transport over the LAN or WAN. 

Question 2: What are FXO and FXS ports?

Answer: 

Foreign Exchange Office (FXO) ports are interfaces used to connect with the central office or PSTN analog lines. Foreign Exchange Station (FXS) ports are interfaces used to connect with end user devices (e.g. phone or fax).

Question 3: What are PSTN failover lines?

Answer: 

PSTN (Public Switched Telephone Network) failover line are used as backup connections in the event your VoIP or Internet connection goes down. These are optional ports on ATA devices or IP phones that connect directly to the analog PSTN lines coming from a telephone company. This setup requires having both regular analog telephone lines and an account any VoIP Service Provider. 

Question 4: Which VoIP signaling protocols are commonly used?

Answer:

VoIP signaling protocols are used to set up and tear down calls, carry the required information to locate end users, and negotiate device capabilities. The following list shows the most common VoIP signaling protocols available: SIP (Session Initiation Protocol), H.323, Cisco SCCP (Skinny Client Control Protocol), IAX (Inter-Asterisk Exchange), and MGCP (Media Gateway Control Protocol).

Question 5: Which voice codec should I use?

Answer:

VoIP codecs convert analog voice signals to their digital encoded version. Codecs vary in size, sound quality, bandwidth and computation requirements. The most common VoIP codecs currently available are: G.711 (alaw & ulaw), G.723, G.726, G.729, GSM, and iLBC.

Question 6: What are Gatekeepers and Registrars?

Answer:

Gatekeepers and Registrars are gateways that provide authentication, call control and call routing, and session invites for end user devices.