V.25bis Commands

V.25bis mode accepts any combination of upper and lower case letters. For async, commands may be terminated by CR or CR/LF pair. Parity bits are ignored.

V.25bis commands are not recognized when DTR is off or when direct addressing is selected (&quotdumb"strap). If DTR goes off when a command has been partially entered, the command buffer is cleared.

Backspace is recognized in async mode, otherwise there is no command line editing.

Character echoing is available (in async mode only) if E1 set in stored profile. There is no character echoing when DTR is low.

In async mode, the modem ignores all control characters (ASCII $00 through $1F, ignoring bit 7) except BS and CR. &quotIgnoring"a character implies the modem does not echo it.

If the command buffer is empty (or has been backspaced away), the modem ignores BS and echoes but otherwise ignores CRs.

In sync modes, control characters not involved in framing (such as STX and ETX, in BSC mode) are treated the same as regular characters (usually resulting in an INV, invalid result code).

Note: If the command line is terminated by a CR/LF pair (async mode), the modem will not echo the LF. When used with a dumb terminal that does not automatically linefeed after CRs, indications (VAL, etc.) overwrites the command just entered.

Command buffer size and maximum dial string length are the same as AT command mode, 256 characters. Command lines that exceed the command buffer size are treated as invalid commands. In async mode, the modem waits until CR is received then responds with an INV result code. In either sync mode, the modem sends an INV result code when the overflow is detected.

In either synchronous mode, improperly framed commands are ignored. Improperly framed means:

HDLC mode: address field not FF, control field not 03 or 13, bad FCS or abort.

BSC mode: first character not STX.

Note: If the ETX is missing at the end of a command string in BSC mode, the modem continues to buffer receive data (probably FFs) until overflow occurs. At this point it issues an INV result code and awaits the next command.)

In V.25bis, command parameters are separated by semicolons (for example, PRN command). Except in the initial three-letter command mnemonic, the command line may include with presentation characters (e.g., space and period). These characters are ignored.

The following commands are implemented:

Command          		Syntax                        Description                                        

CRN Dial a number		CRN <phone-number>           Call request with number                           


CRS Dial stored  		CRS <mem-addr>               Call request using stored number                   

number                                                                                                       


PRN Store a      		PRN<mem-addr><phone-number>  Store number in memory                             

number                                                                                                       


DIC Disregard    		DIC                           Disregard incoming call                            

incoming call                                                                                                


CIC Connect      		CIC                           Connect incoming call                              

incoming call                                                                                                


RST Reset modem  		RST                           Cold reset--nonstandard

Legend:
<mem-addr>for stored numbers must be 0, 1, 2 or 3. V.25bis does not add memory for any additional stored numbers beyond that provided in AT command operation. V.25bis and AT commands share the same stored number memory. You can program the stored numbers in AT command mode then use them in V.25bis mode, and vice versa.

<phone-number>is the dial string defined by V.25bis. Translation to Hayes equivalent dial string is as follows:

V.25bis     Hayes                                                                

0..9        
0..9 (Regular DTMF digits)                                           
                                      

A..D,#, *   A..D,#, * (Other digits not defined by V.25bis but they may be       

            accepted)                                                             
                                                    

:           W (Wait for tone)                                                    
                                                      

<           ,  (Pause)                                                           


&           ! (Flash)                                                            


P           P (Pulse dialing)                                                    

T           T (Tone dialing)

The following V.25bis dial string characters are not accepted: = >No Hayes dial modifiers are accepted in V.25bis mode except for P, T, A, B, C, and D. Otherwise, you must use the V.25bis characters (i.e., & instead of ! for flash, etc.)

V.25bis filters unsupported dial string characters in the same manner as normal AT command mode. V.25bis dial strings are stored in standard Hayes dial string form, so they can be recalled later via ATDS command.

Features such as comma pause time follow the usual Sregister settings. V.25bis does not provide a method to set these parameters.

The RST command is non-standard, it performs a cold reset on the modem, exactly as if power had been cycled off then on. There are no parameters.

The RST command ONLY works when the DIP switches are "UP UP". Other DIP switch settings force normal V.25bis operation without Hayes extensions.

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