Differences: speedtouch 330 vs the older speedtouch USB:
Vendor and ProdID: no difference (!)
Rev: 2.00 vs 0.00
SerialNumber: 0090D0xxxxxx, xxxxxx larger for 330
Interface 1, Alt 2:
	E: Ad=06(O) Atr=02(Bulk) MxPS=64 Ivl=0ms
	E: Ad=07(O) Atr=02(Bulk) MxPS=64 Ivl=0ms
	E: Ad=87(I) Atr=01(Isoc) MxPS=640 Ivl=1ms
vs
	E: Ad=06(O) Atr=02(Bulk) MxPS=32 Ivl=0ms
	E: Ad=07(O) Atr=02(Bulk) MxPS=32 Ivl=0ms
	E: Ad=87(I) Atr=02(Bulk) MxPS=64 Ivl=0ms
Interface 1, Alt 3:
	E: Ad=06(O) Atr=02(Bulk) MxPS=64 Ivl=0ms
	E: Ad=07(O) Atr=02(Bulk) MxPS=64 Ivl=0ms
	E: Ad=87(I) Atr=01(Isoc) MxPS=960 Ivl=1ms
vs
	E: Ad=06(O) Atr=02(Bulk) MxPS=16 Ivl=0ms
	E: Ad=07(O) Atr=02(Bulk) MxPS=16 Ivl=0ms
	E: Ad=87(I) Atr=02(Bulk) MxPS=64 Ivl=0ms
The current driver works with the speedtouch 330 as long as we use alternate setting
1 on interface 1 rather than alternate 2 as we do now.  In fact it makes sense to use
alternate 1 for the speedtouch USB as well: the difference is in the max packet size
for the out bulk endpoint (0x07): 64 for Alt 1, 32 for Alt 2.  Since we send only
multiples of 53 bytes (ATM cell size), the potential lower latency for Alt 2 is not
really exploitable (think about it!).  My tests indicate no harm and perhaps a slight
gain by using Alt 1.  The manufacturer seems to think so too, since they chose to
keep the Alt 1 setting and threw out Alt 2 when designing the 330.  So just use Alt 1
for both modems.