Leased lines are the only solution in SA that absolutely guarantees QOS for your VOIP calls.
Linking multiple offices (data & VOIP) is hard on ADSL as the VOIP calls experience too much jitter, delays and re-transmits.
If separate ADSL lines are used, one for data and one for VOIP, then it's a bit better but call quality is still 4/5 at best.
For data-only, leased lines have become pretty useless.
""Telkom and the rest hope you don't realise this""
I cancelled a 1Mbps Diginet Gold line & replaced it with a normal run-of-the-mill 4mbps 50GB cap ADSL (routed via fiber not sat).
Diginet was 6 times the cost and DSL is twice as fast.
I have a 2nd DSL as backup (still cheaper than LL)
It's MHO that If you run VOIP/want to run VOIP get a DSL line for data, a small leased line for VOIP and a router capable of "multilink"
If either link fails you're still connected, just a tad slower.
And If normal leased line (Diginet/Matis) is not good enough for ya, then our Friends at Telkom can supply a 155Mbps ATM point to point link at roughly R100K rental per month.
moehahaha.