diff --git a/apps/dm/app/store/sdmMng/index.tsx b/apps/dm/app/store/sdmMng/index.tsx
index 0041f5a93..2627909b6 100644
--- a/apps/dm/app/store/sdmMng/index.tsx
+++ b/apps/dm/app/store/sdmMng/index.tsx
@@ -43,6 +43,34 @@ export const sdmInfoFormSchema = z.object({
 
 export type SdmInfoFormData = z.infer<typeof sdmInfoFormSchema>;
 
+const formatTelno = (telno?: string | null) => {
+  const digits = (telno ?? '').replace(/\D/g, '');
+
+  if (!digits) {
+    return '';
+  }
+
+  if (digits.startsWith('02')) {
+    if (digits.length === 9) {
+      return digits.replace(/(02)(\d{3})(\d{4})/, '$1-$2-$3');
+    }
+
+    if (digits.length === 10) {
+      return digits.replace(/(02)(\d{4})(\d{4})/, '$1-$2-$3');
+    }
+  }
+
+  if (digits.length === 10) {
+    return digits.replace(/(\d{3})(\d{3})(\d{4})/, '$1-$2-$3');
+  }
+
+  if (digits.length === 11) {
+    return digits.replace(/(\d{3})(\d{4})(\d{4})/, '$1-$2-$3');
+  }
+
+  return telno ?? '';
+};
+
 
 // 수요처 정보
 export type DemandCompBizType = {
@@ -694,7 +722,7 @@ export const SdmReducer = (set: any): SdmActions => {
           dmdInfoId: res.dmdInfoId,
           zip: res.zip || '',
           daddr: res.daddr,
-          telno: res.telno.replace(/(\d{3})(\d{4})(\d{4})/, '$1-$2-$3'),
+          telno: formatTelno(res.telno),
           rgtr: res.rgtr,
           ctpvCd: res.ctpvCd,
           sggCd: res.sggCd,