VoIP glossary
What is G.711?
G.711 is the standard uncompressed telephone codec, sampling speech at 8 kHz and sending it at 64 kbit/s, in two variants: µ-law (G.711u) in North America and Japan, and A-law (G.711a) almost everywhere else.
G.711 explained
Because it does not compress, G.711 gives the best quality a normal phone line can offer and passes fax tones, modem signals and in-band DTMF reliably. The cost is bandwidth: roughly 87 kbit/s per direction once IP and RTP headers are added.
G.711 is the safest default for a SIP trunk. It is supported by every PBX, phone and carrier, so it avoids transcoding. If bandwidth is not a constraint, put it first in your codec list.
Example
Ten simultaneous G.711 calls use about 870 kbit/s up and 870 kbit/s down, which is easy on a typical office fibre line.
Put it into practice
Prepaid SIP trunks and wholesale routes from $200. Ask sales for rates or the NOC for a technical answer.