Modem Initialization String Command Separators

First, I must comment on the string. A modem command string is executed serially, so what you get when you enter AT+MS=V90&F&C1&D2 s51=95 is:

Attention,
+MS=V90 - Set v.90 as highest protocol,
&F - Reset to factory defaults (wipes out the preceding command plus any that had been entered by the dialler- i.e.the speaker volume),
&C1&D2 - defaults having to do with handling of and DCE - DTE interface
S51=95 - I'd have to look it up.


But if it works for you......

No command seperator is required with these particular commands. Just add the M0 after the &F (so it doesn't get wiped out). AT+MS=V90&FM0&C1&D2S51=95.

Thanks much for your reply and especially for the insight into the string.  I added the M0 and it worked as I wanted. 

Also, I took the &F out, and I still dial up fine--should that be okay?  Or should I leave the &F in?  Or does it not really matter either way?

Thanks for the expertise.

Speechmaker

I'd suggest removal of &C1&D2 also as they are the existaing defaults anyway.

Ideally, you shouldn't need any additional init string. If there is anything in that string that *could* be beneficial, if would be the S51=95 command. S51=95 disables the X2 protocol on a BCM modem. And/or the +MS=V90 command which disables v.92.

X2 was USR/3Com's propriatary 56k protocol that was used prior to the adoption of a 56k standard. It is really an obsolete protocol now.

If the host equipment at your ISP is not X2 compatable and is of a less than recent vintage, it is possible that the X2 signature in the modems orinating handshake is confusing it - resulting in a less than optimum connection. A similar explaination applies to the +MS=V90 command that disables the v.92 protocol.

Bottom line, try the string AT M0 +MS=V90 S51=95 and see if that does the job for you (spaces shown in the string for clarity only).

AT - Attention
M0 - Turn speaker off
+MS=V90 - Disable v.92
S51=95 - Disable X2

Thanks once again.  Works great. 

Speechmaker