diff --git a/components/gitpod-db/src/typeorm/migration/1663784254956-IndexPhoneNumber.ts b/components/gitpod-db/src/typeorm/migration/1663784254956-IndexPhoneNumber.ts
new file mode 100644
index 00000000000000..0b63d0f22a8e6e
--- /dev/null
+++ b/components/gitpod-db/src/typeorm/migration/1663784254956-IndexPhoneNumber.ts
@@ -0,0 +1,23 @@
+/**
+ * Copyright (c) 2022 Gitpod GmbH. All rights reserved.
+ * Licensed under the GNU Affero General Public License (AGPL).
+ * See License-AGPL.txt in the project root for license information.
+ */
+
+import { MigrationInterface, QueryRunner } from "typeorm";
+import { columnExists } from "./helper/helper";
+
+const D_B_USER = "d_b_user";
+const COL_PHONE_NUMBER = "verificationPhoneNumber";
+
+export class IndexPhoneNumber1663784254956 implements MigrationInterface {
+    public async up(queryRunner: QueryRunner): Promise<void> {
+        if (!(await columnExists(queryRunner, D_B_USER, COL_PHONE_NUMBER))) {
+            await queryRunner.query(
+                `ALTER TABLE ${D_B_USER} ADD INDEX (${COL_PHONE_NUMBER}), ALGORITHM=INPLACE, LOCK=NONE `,
+            );
+        }
+    }
+
+    public async down(queryRunner: QueryRunner): Promise<void> {}
+}
diff --git a/components/gitpod-db/src/typeorm/user-db-impl.ts b/components/gitpod-db/src/typeorm/user-db-impl.ts
index 94cbd8c9de9ff9..c6e82aa7233720 100644
--- a/components/gitpod-db/src/typeorm/user-db-impl.ts
+++ b/components/gitpod-db/src/typeorm/user-db-impl.ts
@@ -570,6 +570,22 @@ export class TypeORMUserDBImpl implements UserDB {
     async getByRefreshToken(refreshTokenToken: string): Promise<OAuthToken> {
         throw new Error("Not implemented");
     }
+
+    async countUsagesOfPhoneNumber(phoneNumber: string): Promise<number> {
+        return (await this.getUserRepo())
+            .createQueryBuilder()
+            .where("verificationPhoneNumber = :phoneNumber", { phoneNumber })
+            .getCount();
+    }
+
+    async isBlockedPhoneNumber(phoneNumber: string): Promise<boolean> {
+        const blockedUsers = await (await this.getUserRepo())
+            .createQueryBuilder()
+            .where("verificationPhoneNumber = :phoneNumber", { phoneNumber })
+            .andWhere("blocked = true")
+            .getCount();
+        return blockedUsers > 0;
+    }
 }
 
 export class TransactionalUserDBImpl extends TypeORMUserDBImpl {
diff --git a/components/gitpod-db/src/user-db.ts b/components/gitpod-db/src/user-db.ts
index 88e798d2e08325..a022b08eb70049 100644
--- a/components/gitpod-db/src/user-db.ts
+++ b/components/gitpod-db/src/user-db.ts
@@ -146,6 +146,8 @@ export interface UserDB extends OAuthUserRepository, OAuthTokenRepository {
     storeGitpodToken(token: GitpodToken & { user: DBUser }): Promise<void>;
     deleteGitpodToken(tokenHash: string): Promise<void>;
     deleteGitpodTokensNamedLike(userId: string, namePattern: string): Promise<void>;
+    countUsagesOfPhoneNumber(phoneNumber: string): Promise<number>;
+    isBlockedPhoneNumber(phoneNumber: string): Promise<boolean>;
 }
 export type PartialUserUpdate = Partial<Omit<User, "identities">> & Pick<User, "id">;
 
diff --git a/components/server/src/auth/verification-service.ts b/components/server/src/auth/verification-service.ts
index 8db34ca2111d5c..1993b48818155b 100644
--- a/components/server/src/auth/verification-service.ts
+++ b/components/server/src/auth/verification-service.ts
@@ -10,13 +10,14 @@ import { inject, injectable, postConstruct } from "inversify";
 import { Config } from "../config";
 import { Twilio } from "twilio";
 import { ServiceContext } from "twilio/lib/rest/verify/v2/service";
-import { WorkspaceDB } from "@gitpod/gitpod-db/lib";
+import { UserDB, WorkspaceDB } from "@gitpod/gitpod-db/lib";
 import { ConfigCatClientFactory } from "@gitpod/gitpod-protocol/lib/experiments/configcat-server";
 
 @injectable()
 export class VerificationService {
     @inject(Config) protected config: Config;
     @inject(WorkspaceDB) protected workspaceDB: WorkspaceDB;
+    @inject(UserDB) protected userDB: UserDB;
     @inject(ConfigCatClientFactory) protected readonly configCatClientFactory: ConfigCatClientFactory;
 
     protected verifyService: ServiceContext;
@@ -59,6 +60,14 @@ export class VerificationService {
         if (!this.verifyService) {
             throw new Error("No verification service configured.");
         }
+        const isBlockedNumber = this.userDB.countUsagesOfPhoneNumber(phoneNumber);
+        const usages = await this.userDB.countUsagesOfPhoneNumber(phoneNumber);
+        if (usages > 3) {
+            throw new Error("The given phone number has been used more than three times.");
+        }
+        if (await isBlockedNumber) {
+            throw new Error("The given phone number is blocked due to abuse.");
+        }
         const verification = await this.verifyService.verifications.create({ to: phoneNumber, channel: "sms" });
         log.info("Verification code sent", { phoneNumber, status: verification.status });
     }