Techie question

lebowsky

I'm currently looking into a project to replace existing analogue lines with multiport ata's and adsl connections on various sites across the country.

I've got a few questions.

How may calls can be made simultaneously (outbound) on a standard adsl connection ?

Am I right in thinking that a voip call would only use the upload side of the adsl connection and what would happen when the number of voip calls exceeds the upload capacity?

The project depends on converting the maximum amount of lines to voip.

Thanks in advance

MickyJoe

Phone calls are two way and so will require bandwidth upload and download.

Typical G711 conversation on my AVM Fritz!box takes about 80Kb each way.

If you're doing multi-site then consider professional equipment like Quintum. Quintum to Quintum calls using their Packet Saver software only needs about 16Kb per call.

penfold944

lebowsky wrote: »

Am I right in thinking that a voip call would only use the upload side of the adsl connection and what would happen when the number of voip calls exceeds the upload capacity?

you also have to consider the cell overhead on adsl. A typical G.729 call ( which is about 24k without header compression ) in fact uses about 80kb/s of bandwidth due to cell padding and wastage of ATM.

So - in short it depends on your upload, but reckon on about 80kb/s per concurrent call for G.729, about 120kb/s for G.711 etc

And unless you do some sort of call admission control to limit the amount of calls to less than the upload bandwidth, then ALL calls will suffer equally if you go over the upload bandwidth as they will all start dropping packets.