diff --git a/shared/helpers/openapi/__snapshots__/generateOpenapi.test.ts.snap b/shared/helpers/openapi/__snapshots__/generateOpenapi.test.ts.snap
index 237a04b5e..6c0870907 100644
--- a/shared/helpers/openapi/__snapshots__/generateOpenapi.test.ts.snap
+++ b/shared/helpers/openapi/__snapshots__/generateOpenapi.test.ts.snap
@@ -63,11 +63,13 @@ exports[`generateOpenApiSchema > should generate proper schema 1`] = `
           "applicant_first_name": {
             "description": "Prenom du candidat",
             "maxLength": 50,
+            "minLength": 1,
             "type": "string",
           },
           "applicant_last_name": {
             "description": "Nom du candidat",
             "maxLength": 50,
+            "minLength": 1,
             "type": "string",
           },
           "applicant_phone": {
diff --git a/shared/helpers/zodHelpers/zodPrimitives.ts b/shared/helpers/zodHelpers/zodPrimitives.ts
index b304152d7..2e356e88a 100644
--- a/shared/helpers/zodHelpers/zodPrimitives.ts
+++ b/shared/helpers/zodHelpers/zodPrimitives.ts
@@ -40,7 +40,7 @@ export const extensions = {
       .string()
       .trim()
       .transform((value) => removeUrlsFromText(value)), /// is it a phone extensions still ??
-  telephone: z.string().trim().refine(validatePhone, { message: "Phone number is not valid. Please use international format prefix (example: +33 for France)" }),
+  telephone: z.string().trim().refine(validatePhone, { message: "Invalid Phone Number: please use international format (+33XXX...) or national format (06XXX...)" }),
   code_naf: () =>
     z.preprocess(
       (v: unknown) => (typeof v === "string" ? v.replace(".", "") : v), // parfois, le code naf contient un point
diff --git a/shared/i18n/i18n.ts b/shared/i18n/i18n.ts
new file mode 100644
index 000000000..7a9f56b86
--- /dev/null
+++ b/shared/i18n/i18n.ts
@@ -0,0 +1,20 @@
+import i18next from "i18next"
+import { z } from "zod"
+import { makeZodI18nMap, zodI18nMap } from "zod-i18n-map"
+import zodEn from "zod-i18n-map/locales/en/zod.json"
+import zodFr from "zod-i18n-map/locales/fr/zod.json"
+
+// lng and resources key depend on your locale.
+i18next.init({
+  lng: "en",
+  resources: {
+    fr: { zod: zodFr },
+    en: { zod: zodEn },
+  },
+})
+z.setErrorMap(zodI18nMap)
+
+export const setZodLanguage = (language: "fr" | "en") => {
+  i18next.changeLanguage(language)
+  z.setErrorMap(makeZodI18nMap({ t: i18next.t }))
+}
diff --git a/shared/models/applications.model.ts b/shared/models/applications.model.ts
index 20721f4ce..5d37ce7e0 100644
--- a/shared/models/applications.model.ts
+++ b/shared/models/applications.model.ts
@@ -1,3 +1,4 @@
+import { ObjectId } from "bson"
 import { Jsonify } from "type-fest"
 
 import { LBA_ITEM_TYPE, LBA_ITEM_TYPE_OLD, allLbaItemType, allLbaItemTypeOLD } from "../constants/lbaitem"
@@ -21,18 +22,20 @@ export enum ApplicationScanStatus {
 export const ZApplication = z
   .object({
     _id: zObjectId,
-    applicant_email: z.string({ required_error: "⚠ L'adresse e-mail est obligatoire" }).email("⚠ Adresse e-mail invalide").describe("Email du candidat"),
+    applicant_email: z.string().email().describe("Email du candidat"),
     applicant_first_name: z
-      .string({ required_error: "⚠ Le prénom est obligatoire" })
+      .string()
+      .min(1)
       .max(50)
       .transform((value) => removeUrlsFromText(value))
       .describe("Prenom du candidat"),
     applicant_last_name: z
-      .string({ required_error: "⚠ Le nom est obligatoire" })
+      .string()
+      .min(1)
       .max(50)
       .transform((value) => removeUrlsFromText(value))
       .describe("Nom du candidat"),
-    applicant_phone: extensions.phone().describe("Téléphone du candidat"),
+    applicant_phone: extensions.telephone.describe("Téléphone du candidat"),
     applicant_attachment_name: z
       .string({ required_error: "⚠ La pièce jointe est obligatoire" })
       .regex(/((.*?))(\.)+(docx|pdf)$/i)
@@ -187,6 +190,9 @@ export const ZApplicationApiPayload = ZApplicationV2Base.extend({
     .string()
     .transform((recipientId) => {
       const [collectionName, jobId] = recipientId.split("_")
+      if (!ObjectId.isValid(jobId)) {
+        throw new Error(`Invalid job identifier: ${jobId}`)
+      }
       if (!["recruteurslba", "jobs_parnters", "recruiters"].includes(collectionName)) {
         throw new Error(`Invalid collection name: ${collectionName}`)
       }
diff --git a/shared/package.json b/shared/package.json
index 532d53260..abd96ea7c 100644
--- a/shared/package.json
+++ b/shared/package.json
@@ -19,12 +19,14 @@
     "@fastify/swagger": "^8.15.0",
     "bson": "^6.7.0",
     "dayjs": "^1.11.13",
+    "i18next": "^24.0.5",
     "libphonenumber-js": "^1.11.7",
     "lodash-es": "^4.17.21",
     "luhn": "^2.4.1",
     "openapi3-ts": "^4.4.0",
     "type-fest": "^4.26.0",
     "zod": "3.23.8",
+    "zod-i18n-map": "^2.27.0",
     "zod-mongodb-schema": "^1.0.2"
   },
   "devDependencies": {
diff --git a/ui/components/ItemDetail/CandidatureLba/services/getSchema.ts b/ui/components/ItemDetail/CandidatureLba/services/getSchema.ts
index 467c6c295..1a97a00db 100644
--- a/ui/components/ItemDetail/CandidatureLba/services/getSchema.ts
+++ b/ui/components/ItemDetail/CandidatureLba/services/getSchema.ts
@@ -1,4 +1,5 @@
 import { IApplicationApiPayloadJSON, ZApplicationApiPayload } from "shared"
+import { validatePhone } from "shared/validators/phoneValidator"
 import { z } from "zod"
 
 import { sessionStorageGet } from "@/utils/localStorage"
@@ -24,8 +25,5 @@ export const ApplicationFormikSchema = ZApplicationApiPayload.pick({
   applicant_email: true,
   applicant_attachment_name: true,
 }).extend({
-  applicant_phone: z
-    .string({ required_error: "⚠ Le numéro de téléphone est obligatoire" })
-    .min(10, "le téléphone est sur 10 chiffres")
-    .max(10, "le téléphone est sur 10 chiffres"), // KBA 2024-12-04: based application schema needs to be changed
+  applicant_phone: z.string().trim().refine(validatePhone, { message: "Téléphone non valide : veuillez utiliser le format international (+33XXX...) ou national (06XXX...)" }),
 })
diff --git a/ui/pages/_app.tsx b/ui/pages/_app.tsx
index 2a46eb254..08335a330 100644
--- a/ui/pages/_app.tsx
+++ b/ui/pages/_app.tsx
@@ -1,6 +1,7 @@
 import { init } from "@socialgouv/matomo-next"
 import { useRouter } from "next/router"
 import { useEffect } from "react"
+import { setZodLanguage } from "shared/i18n/i18n"
 
 import { setIsTrackingEnabled, setTrackingCookies } from "@/common/utils/trackingCookieUtils"
 
@@ -18,6 +19,7 @@ export default function LaBonneAlternance({ Component, pageProps }) {
   const router = useRouter()
 
   useEffect(() => {
+    setZodLanguage("fr")
     init(publicConfig.matomo)
     setIsTrackingEnabled()
   }, [])
diff --git a/yarn.lock b/yarn.lock
index 7816f8957..d2552efc4 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -13156,6 +13156,20 @@ __metadata:
   languageName: node
   linkType: hard
 
+"i18next@npm:^24.0.5":
+  version: 24.0.5
+  resolution: "i18next@npm:24.0.5"
+  dependencies:
+    "@babel/runtime": ^7.23.2
+  peerDependencies:
+    typescript: ^5
+  peerDependenciesMeta:
+    typescript:
+      optional: true
+  checksum: ae5bc37682f14f4ee44450e10598d32edd324edba2d0980339aa232cdfd506174a2e2dd7b9204d2882c28ddc37261c26c6b7b153ff586e54be71e27599d3dbf8
+  languageName: node
+  linkType: hard
+
 "iconv-lite@npm:0.4.24, iconv-lite@npm:^0.4.24":
   version: 0.4.24
   resolution: "iconv-lite@npm:0.4.24"
@@ -20678,6 +20692,7 @@ __metadata:
     bson: ^6.7.0
     dayjs: ^1.11.13
     eslint-plugin-zod: ^1.4.0
+    i18next: ^24.0.5
     libphonenumber-js: ^1.11.7
     lodash-es: ^4.17.21
     luhn: ^2.4.1
@@ -20686,6 +20701,7 @@ __metadata:
     type-fest: ^4.26.0
     typescript: ^5.4.5
     zod: 3.23.8
+    zod-i18n-map: ^2.27.0
     zod-mongodb-schema: ^1.0.2
   languageName: unknown
   linkType: soft
@@ -23456,6 +23472,16 @@ __metadata:
   languageName: node
   linkType: hard
 
+"zod-i18n-map@npm:^2.27.0":
+  version: 2.27.0
+  resolution: "zod-i18n-map@npm:2.27.0"
+  peerDependencies:
+    i18next: ">=21.3.0"
+    zod: ">=3.17.0"
+  checksum: 9c06867e6f8ee883ccde1b980477563409cf89759a7af345cafd2da5a3d241892f3372e37ddf482a7b7dc40602079292870b64c3c82263141feae341b80da1c1
+  languageName: node
+  linkType: hard
+
 "zod-mongodb-schema@npm:^1.0.2":
   version: 1.0.2
   resolution: "zod-mongodb-schema@npm:1.0.2"