This isn't really a bug as such, but something I've needed since going
online via Orange (a UK cellular network). The patch below adds a retry
function to chat.. It's built against the latest ppp SRPM.

How to use: RETRY <expect string, e.g. BUSY>
            RETRCMD <command, e.g. ATDT08450798666>
            RETREXP <expect string to carry on as normal>

If on retrying the RETRY expect string is encountered, it'll try again...

Patch begins (patch for man page omitted, available on request):

--- ppp-2.3.10/chat/chat.c.old  Mon Sep  6 06:10:23 1999
+++ ppp-2.3.10/chat/chat.c      Sat Dec  4 03:42:45 1999
@@ -14,6 +14,10 @@
  *     This software is in the public domain.
  *
  * -----------------
+ *     04-Dec-99 added RETRY support. A really horrible hack. Vaguely
+ *     documented in the man page. It probably could be better...
+ *     Michael McConnell <soruk.uk>
+ *
  *     22-May-99 added environment substitutuion, enabled with -E switch.
  *     Andreas Arens <andras>.
  *
@@ -201,6 +205,8 @@
        fail_buffer[50];
 int n_aborts = 0, abort_next = 0, timeout_next = 0, echo_next = 0;
 int clear_abort_next = 0;
+int retry_next = 0, retry_set = 0, retry_cmd_next = 0, retry_exp_next = 0;
+char retry_string[32], retry_cmd[256], retry_exp[32];

 char *report_string[MAX_REPORTS] ;
 char  report_buffer[50] ;
@@ -909,6 +920,21 @@
        return;
     }

+    if (strcmp(s, "RETRY") == 0) {
+       ++retry_next;
+       return;
+    }
+
+    if (strcmp(s, "RETRCMD") == 0) {
+       ++retry_cmd_next;
+       return;
+    }
+
+    if (strcmp(s, "RETREXP") == 0) {
+       ++retry_exp_next;
+       return;
+    }
+
     if (strcmp(s, "CLR_ABORT") == 0) {
        ++clear_abort_next;
        return;
@@ -1147,6 +1173,37 @@
        return;
     }

+    if (retry_next) {
+       retry_next = 0;
+       strcpy(retry_string, s);
+       retry_set = 1;
+
+       if (verbose)
+           logf("Retry string set to %s", retry_string);
+
+       return;
+    }
+
+    if (retry_exp_next) {
+       retry_exp_next = 0;
+       strcpy(retry_exp, s);
+
+       if (verbose)
+           logf("Retry expect string set to %s", retry_exp);
+
+       return;
+    }
+
+    if (retry_cmd_next) {
+       retry_cmd_next = 0;
+       strcpy(retry_cmd, s);
+
+       if (verbose)
+           logf("Retry command set to %s", retry_cmd);
+
+       return;
+    }
+
     /*
      * The syntax @filename means read the string to send from the
      * file `filename'.
@@ -1379,7 +1436,7 @@
     alarmed = 0;

     while ( ! alarmed && (c = get_char()) >= 0) {
-       int n, abort_len, report_len;
+       int n, retry_len, abort_len, report_len;

        if (echo)
            echo_stderr(c);
@@ -1446,6 +1503,19 @@
            alarm(0);
            alarmed = 0;
            return (1);
+       }
+
+       if (s - temp >= (retry_len = strlen(retry_string)) && retry_set &&
+         strncmp(s - retry_len, retry_string, retry_len-2) == 0) {
+           if (verbose) {
+               if (1)
+                   logf("[%s]", retry_string);
+               logf(" -- Retrying");
+           }
+           /* Bung in here the commands to send retry_cmd */
+           put_string(retry_cmd);
+           get_string(retry_exp);
+           return(1);
        }

        for (n = 0; n < n_aborts; ++n) {