I was having some odd connection problems with my Apple powerbook internal v90 modem. Random connection failures and disconnections. So I started looking at the modem script (inside /library/modem scripts). I read somewhere that with modems it's better to start simple so I commented out the existing init string and replaced it.
I replaced:
write "AT&FE0W1Q0V1X4&C1&K3S95=1&D3S7=75S0=013"with
write "AT&F13"(Note: The exact line in the script may be different from that shown above, there are several versions of it. In the apple script it is below "label 3")
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