How many VoIP lines can you have over DSL?

The number of simultaneous VoIP calls that can be placed over DSL depends largely on two things:

1. Your available upstream DSL bandwidth (generally 640-800Kb upstream)
2. The codec* your VoIP provider permits you to use (normally G.729a or G.711).

I won’t get into the details of DSL or the codecs, because the real question is how many lines can somebody realistically put over DSL.  However, I’d be happy to answer any questions should they arise.

G.729 typically uses about 32Kbps while G.711 will consume approximately 90Kbps.  In an ideal world, this means about 8 calls… but you’ll never see that.  We typically recommend no more than 3-4 simultaneous calls over DSL.  See my previous posting regarding Business VoIP over DSL: Viable for Business?

*A codec encodes/decodes voice traffic for transmission over IP