Active Profile After Power-On
When the modem powers-on, it loads one of two stored profiles: 0 or
1. The &Y command selects which stored profile is loaded at power-on. If
&Y0 is in effect, then profile-0 should be loaded at power-on, while &Y1 selects
profile-1. The Z command performs a soft reset, which involves loading one
of the stored profiles. ATZ or ATZ0 loads profile-0, while ATZ1 loads profile-1.
V.25bis does not change any of this. However, these profiles are overridden
at power-up if a V.25 mode is selected by the switches.
When the modem enters V.25bis mode (according to the above process), some
additional settings are also overridden. These are as follows:
&Qn - acts like &Q5 (if async) or like &Q1 (if sync)
&Dn - acts like &D2
&Sn - acts like &S2
S0 - acts like S0=1
The reason for overriding these settings is to obtain behavior conforming
to the V.25bis standard. Note that this only pertains to V.25bis state,
not AT command state.
Note: Overriding a setting does not change its value, either in the
active profile or a stored profile.
Also overriding a setting does not change the value seen when the user displays
that setting (with the &V or S? command). Overriding means that the modem
BEHAVES as if that setting were changed, without actually affecting its
value.
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