diff --git a/configs/samples/cdr_custom.conf.sample b/configs/samples/cdr_custom.conf.sample
index 760c039eba..3a120428a3 100644
--- a/configs/samples/cdr_custom.conf.sample
+++ b/configs/samples/cdr_custom.conf.sample
@@ -106,7 +106,8 @@
     ;
     ; The default output format for the "start", "answer" and "end" timestamp fields
     ; is the "%Y-%m-%d %T" strftime string format however you can also format those
-    ; fields as an int64 or a float: `start(int64),answer(float),end`.
+    ; fields as an int64 or a double: `start(int64)` or `start(double)` or
+    ; provide your own strftime format string: `start(%FT%T%z)`.
     ;
     ; The "disposition" and "amaflags" are formatted as their string names like
     ; "ANSWERED" and "DOCUMENTATION" by default but if you just want the numbers and
diff --git a/configs/samples/cel_custom.conf.sample b/configs/samples/cel_custom.conf.sample
index 03debc6e29..e025dd6bf1 100644
--- a/configs/samples/cel_custom.conf.sample
+++ b/configs/samples/cel_custom.conf.sample
@@ -111,9 +111,12 @@
     ; you can force the uniqueid field to not be quoted with `uniqueid(noquote)`. The
     ; example in fields above shows this.
     ;
-    ; The default output format for the "EventTime" timestamp field is the "%Y-%m-%d %T"
-    ; strftime string format however you can also format the field as an int64 or a
-    ; float: `eventtime(int64)` or `eventtime(float)`.
+    ; The default output format for the "EventTime" timestamp field is taken from the
+    ; "dateformat" parameter in cel.conf.  If that's not set, the default is
+    ; "<seconds>.<microseconds>" where "<microseconds>" is always 6 digits with
+    ; leading zeros.  You can also format the field as an int64 or a double:
+    ; `eventtime(int64)` or `eventtime(double)` or provide your own strftime
+    ; format string: `eventtime(%FT%T%z)`.
     ;
     ; Unlike CDRs, the "amaflags" field is output as its numerical value by default
     ; for historical reasons.  You can output it as its friendly string with
diff --git a/res/cdrel_custom/cdrel.h b/res/cdrel_custom/cdrel.h
index 84787840e9..e1542b7db4 100644
--- a/res/cdrel_custom/cdrel.h
+++ b/res/cdrel_custom/cdrel.h
@@ -78,12 +78,13 @@ enum cdrel_data_type {
 	cdrel_type_uservar,
 	cdrel_type_event_type,
 	cdrel_type_event_enum,
+	cdrel_type_cel_timefmt,
 	cdrel_data_type_strings_end,
 	cdrel_type_int32,
 	cdrel_type_uint32,
 	cdrel_type_int64,
 	cdrel_type_uint64,
-	cdrel_type_float,
+	cdrel_type_double,
 	cdrel_data_type_end
 };
 
@@ -180,7 +181,7 @@ struct cdrel_value {
 		int64_t int64;
 		uint64_t uint64;
 		struct timeval tv;
-		float floater;
+		double doubler;
 	} values;
 };
 
diff --git a/res/cdrel_custom/config.c b/res/cdrel_custom/config.c
index d4655f0792..49543df3d2 100644
--- a/res/cdrel_custom/config.c
+++ b/res/cdrel_custom/config.c
@@ -432,6 +432,7 @@ static struct cdrel_field *field_alloc(struct cdrel_config *config, const char *
 			if (strchr(qualifier, '%') != NULL) {
 				data_swap = ast_strdupa(qualifier);
 				ast_set_flag(&field_flags, cdrel_flag_format_spec);
+				forced_output_data_type = cdrel_type_string;
 				ast_debug(3, "   Using qualifier '%s' for field '%s' flags: %s\n", qualifier,
 					field_name, ast_str_tmp(128, cdrel_get_field_flags(&field_flags, &STR_TMP)));
 			}
@@ -466,6 +467,17 @@ static struct cdrel_field *field_alloc(struct cdrel_config *config, const char *
 		return NULL;
 	}
 
+	if (ast_test_flag(&field_flags, cdrel_flag_format_spec)
+		&& registered_field->input_data_type != cdrel_type_timeval) {
+		ast_log(LOG_WARNING, "%s->%s: Custom format '%s' ignored for field '%s'."
+			" Only timeval types can use custom format strings.\n",
+			cdrel_basename(config->config_filename), cdrel_basename(config->output_filename),
+			data, field_name);
+		forced_output_data_type = cdrel_data_type_end;
+		ast_clear_flag(&field_flags, cdrel_flag_format_spec);
+		data = NULL;
+	}
+
 	field = ast_calloc(1, sizeof(*registered_field) + strlen(input_field_template) + 1);
 	if (!field) {
 		return NULL;
@@ -1127,7 +1139,7 @@ static struct cdrel_config *load_text_file_legacy_config(enum cdrel_record_type
 		return NULL;
 	}
 
-	ast_log(LOG_NOTICE, "%s->%s: Logging %s records\n",
+	ast_log(LOG_NOTICE, "%s->%s: Logging legacy %s records as advanced\n",
 		cdrel_basename(config->config_filename), cdrel_basename(config->output_filename),
 		RECORD_TYPE_STR(config->record_type));
 
diff --git a/res/cdrel_custom/formatters.c b/res/cdrel_custom/formatters.c
index fc4e22a5dc..2be6d26cb6 100644
--- a/res/cdrel_custom/formatters.c
+++ b/res/cdrel_custom/formatters.c
@@ -118,7 +118,7 @@ DEFINE_FORMATTER(uint32, uint32, uint32_t, "%u")
 DEFINE_FORMATTER(int32, int32, int32_t, "%d")
 DEFINE_FORMATTER(uint64, uint64, uint64_t, "%lu")
 DEFINE_FORMATTER(int64, int64, int64_t, "%ld")
-DEFINE_FORMATTER(float, floater, float, "%.1f")
+DEFINE_FORMATTER(double, doubler, double, "%.6f")
 
 static int format_timeval(struct cdrel_config *config,
 	struct cdrel_field *field, struct cdrel_value *input_value, struct cdrel_value *output_value)
@@ -134,11 +134,20 @@ static int format_timeval(struct cdrel_config *config,
 		output_value->data_type = cdrel_type_int64;
 		output_value->values.int64 = input_value->values.tv.tv_sec;
 		return format_int64(config, field, output_value, output_value);
-	} else if (field->output_data_type == cdrel_type_float) {
-		output_value->data_type = cdrel_type_float;
-		output_value->values.floater = ((float)input_value->values.tv.tv_sec) + ((float)input_value->values.tv.tv_usec) / 1000000.0;
-		return format_float(config, field, output_value, output_value);
-	} else 	if (!ast_strlen_zero(field->data)) {
+	} else if (field->output_data_type == cdrel_type_double) {
+		output_value->data_type = cdrel_type_double;
+		output_value->values.doubler = ((double)input_value->values.tv.tv_sec) + ((double)input_value->values.tv.tv_usec) / 1000000.0;
+		return format_double(config, field, output_value, output_value);
+	} else if (field->output_data_type == cdrel_type_cel_timefmt) {
+		res = ast_cel_format_eventtime(input_value->values.tv, tempbuf, 64);
+		if (res != 0) {
+			return res;
+		}
+		input_value->values.string = tempbuf;
+		input_value->data_type = cdrel_type_string;
+		output_value->data_type = cdrel_type_string;
+		return format_string(config, field, input_value, output_value);
+	} else if (!ast_strlen_zero(field->data)) {
 		format = field->data;
 	}
 
@@ -186,7 +195,7 @@ int load_formatters(void)
 	cdrel_field_formatters[cdrel_type_int64] = format_int64;
 	cdrel_field_formatters[cdrel_type_uint64] = format_uint64;
 	cdrel_field_formatters[cdrel_type_timeval] = format_timeval;
-	cdrel_field_formatters[cdrel_type_float] = format_float;
+	cdrel_field_formatters[cdrel_type_double] = format_double;
 	cdrel_field_formatters[cdrel_type_amaflags] = format_amaflags;
 	cdrel_field_formatters[cdrel_type_disposition] = format_disposition;
 
diff --git a/res/cdrel_custom/getters_cdr.c b/res/cdrel_custom/getters_cdr.c
index 45667db57e..8e87cb25a1 100644
--- a/res/cdrel_custom/getters_cdr.c
+++ b/res/cdrel_custom/getters_cdr.c
@@ -53,7 +53,7 @@ DEFINE_CDR_GETTER(uint32, uint32, uint32_t)
 DEFINE_CDR_GETTER(int64, int64, int64_t)
 DEFINE_CDR_GETTER(uint64, uint64, uint64_t)
 DEFINE_CDR_GETTER(tv, timeval, struct timeval)
-DEFINE_CDR_GETTER(floater, float, float)
+DEFINE_CDR_GETTER(doubler, double, double)
 
 static int cdr_get_literal(void *record, struct cdrel_config *config,
 	struct cdrel_field *field, struct cdrel_value *value)
@@ -108,7 +108,7 @@ int load_cdr(void)
 	cdrel_field_getters[cdrel_record_cdr][cdrel_type_int64] = cdr_get_int64;
 	cdrel_field_getters[cdrel_record_cdr][cdrel_type_uint64] = cdr_get_uint64;
 	cdrel_field_getters[cdrel_record_cdr][cdrel_type_timeval] = cdr_get_timeval;
-	cdrel_field_getters[cdrel_record_cdr][cdrel_type_float] = cdr_get_float;
+	cdrel_field_getters[cdrel_record_cdr][cdrel_type_double] = cdr_get_double;
 	cdrel_field_getters[cdrel_record_cdr][cdrel_type_uservar] = cdr_get_uservar;
 	cdrel_dummy_channel_allocators[cdrel_record_cdr] = dummy_chan_alloc_cdr;
 
diff --git a/res/cdrel_custom/registry.c b/res/cdrel_custom/registry.c
index 472b147c45..da678aee03 100644
--- a/res/cdrel_custom/registry.c
+++ b/res/cdrel_custom/registry.c
@@ -47,7 +47,7 @@
 static const struct cdrel_field cdrel_field_registry[] = {
 	REGISTER_FIELD(cdrel_record_cel, AST_EVENT_IE_CEL_EVENT_ENUM, "eventenum", cdrel_type_event_enum, cdrel_type_string),
 	REGISTER_FIELD(cdrel_record_cel, AST_EVENT_IE_CEL_EVENT_TYPE, "eventtype", cdrel_type_event_type, cdrel_type_string),
-	REGISTER_FIELD(cdrel_record_cel, AST_EVENT_IE_CEL_EVENT_TIME, "eventtime", cdrel_type_timeval, cdrel_type_string),
+	REGISTER_FIELD(cdrel_record_cel, AST_EVENT_IE_CEL_EVENT_TIME, "eventtime", cdrel_type_timeval, cdrel_type_cel_timefmt),
 	REGISTER_FIELD(cdrel_record_cel, AST_EVENT_IE_CEL_EVENT_TIME_USEC, "eventtimeusec", cdrel_type_uint32, cdrel_type_uint32),
 	REGISTER_FIELD(cdrel_record_cel, AST_EVENT_IE_CEL_USEREVENT_NAME, "usereventname", cdrel_type_string, cdrel_type_string),
 	REGISTER_FIELD(cdrel_record_cel, AST_EVENT_IE_CEL_USEREVENT_NAME, "userdeftype", cdrel_type_string, cdrel_type_string),
diff --git a/res/res_cdrel_custom.c b/res/res_cdrel_custom.c
index 179db87acc..773007a345 100644
--- a/res/res_cdrel_custom.c
+++ b/res/res_cdrel_custom.c
@@ -166,12 +166,13 @@ const char *cdrel_data_type_map[] = {
 	[cdrel_type_uservar] = "uservar",
 	[cdrel_type_event_type] = "event_type",
 	[cdrel_type_event_enum] = "event_enum",
+	[cdrel_type_cel_timefmt] = "cel_timefmt",
 	[cdrel_data_type_strings_end] = "!!STRINGS END!!",
 	[cdrel_type_int32] = "int32",
 	[cdrel_type_uint32] = "uint32",
 	[cdrel_type_int64] = "int64",
 	[cdrel_type_uint64] = "uint64",
-	[cdrel_type_float] = "float",
+	[cdrel_type_double] = "double",
 	[cdrel_data_type_end] = "!!END!!",
 };