>I've used my regular V3 to tether and it's slightly faster than dial up
That's because it only has GPRS, not EGPRS(EDGE), much less UMTS.
>however I've used my V551 and it's was faster.
Because it supports EGPRS(EDGE), albeit not the fastest form of EGPRS.
>As for the V3x I
>believe that has the UMTS service so if you are in a market with UMTS
>you should get pretty good speeds.
No, because it doesn't support the UMTS band used by Cingular. Also doesn't
support EGPRS(EDGE), so it won't be any faster than the regular V3, slower
than the V551.
>I used Cingular's communication manager program to tether but Moto
>Phone tools seemed to work better for me.
Windows DUN (dial-up networking) is all that's needed. See the FAQ below.

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Best regards, SEE THE FAQ FOR CINGULAR WIRELESS AT
John Navas <http://en.wikibooks.org/wiki/Cingular_Wireless_FAQ>