diff --git a/src/Center/Center.ts b/src/Center/Center.ts
index 2a3d4c6..f2e060e 100644
--- a/src/Center/Center.ts
+++ b/src/Center/Center.ts
@@ -273,6 +273,10 @@ export class Center implements SmppSession {
 		this.defaultSingleJob = job;
 	}
 
+	getPort(): number {
+		return this.port;
+	}
+
 	private validateSessions(reject: (reason?: any) => void) {
 		if (this.sessions.length === 0) {
 			reject(`No clients connected`);
diff --git a/src/Center/CenterSessionManager.ts b/src/Center/CenterSessionManager.ts
new file mode 100644
index 0000000..dd5ca23
--- /dev/null
+++ b/src/Center/CenterSessionManager.ts
@@ -0,0 +1,85 @@
+import EventEmitter from "events";
+import fs from "fs";
+import {Job} from "../Job/Job";
+import Logger from "../Logger";
+import {SessionManager} from "../SessionManager";
+import {SmppSession} from "../SmppSession";
+import {Center} from "./Center";
+
+const CENTER_SESSIONS_FILE: string = process.env.CENTER_SESSIONS_FILE || "center_sessions.json";
+
+export class CenterSessionManager extends SessionManager {
+	sessionId: number = 0;
+	sessions: Center[] = [];
+	identifier: string = "center";
+	readonly logger: Logger = new Logger("CenterSessionManager");
+	readonly eventEmitter: EventEmitter = new EventEmitter();
+
+	constructor() {
+		super();
+		// super.eventEmitter.on(super.SESSION_ADDED_EVENT, (session: SmppSession) => this.eventEmitter.emit(this.SESSION_ADDED_EVENT, session));
+	}
+
+	setup(): void {
+		try {
+			this.logger.log1(`Loading clients from ${CENTER_SESSIONS_FILE}`)
+			let sessions: Buffer = fs.readFileSync(CENTER_SESSIONS_FILE);
+			let loadedSessions: any[] = JSON.parse(String(sessions));
+			this.logger.log1(`Loaded ${loadedSessions.length} clients from ${CENTER_SESSIONS_FILE}`);
+			loadedSessions.forEach(session => {
+				this.createSession(session.url, session.username, session.password).then((sessionObj: SmppSession) => {
+					sessionObj.setDefaultSingleJob(Job.deserialize(session.defaultSingleJob));
+					sessionObj.setDefaultMultipleJob(Job.deserialize(session.defaultMultipleJob));
+				});
+			});
+		} catch (e) {
+			this.logger.log1(`Error loading clients from ${CENTER_SESSIONS_FILE}: ${e}`);
+			return;
+		}
+	}
+
+	cleanup(): void {
+		this.logger.log1(`Saving clients to ${CENTER_SESSIONS_FILE}...`);
+		fs.writeFileSync(CENTER_SESSIONS_FILE, JSON.stringify(this.serialize(), null, 4));
+	}
+
+	createSession(port: number, username: string, password: string): Promise<SmppSession> {
+		return new Promise<SmppSession>((resolve, reject) => {
+			this.logger.log1(`Creating session with port ${port}`);
+			this.getSessionByPort(port).then(s => {
+				resolve(s);
+			}, err => {
+			});
+			this.verifyPort(port, reject);
+			this.verifyUsername(username, reject);
+			this.verifyPassword(password, reject);
+
+			let client = new Center(this.sessionId++, port, username, password);
+			this.addSession(client).then(() => {
+				resolve(client);
+			});
+		});
+	}
+
+	getSessionByPort(port: number): Promise<SmppSession> {
+		return new Promise<SmppSession>((resolve, reject) => {
+			this.logger.log1(`Looking for session with port ${port}...`);
+			let session: SmppSession | undefined = this.sessions.find((s: Center) => s.getPort() === port);
+			if (session) {
+				this.logger.log1(`Found session with port ${port}`);
+				resolve(session);
+			} else {
+				this.logger.log1(`Session with port ${port} not found`);
+				reject(`Session with port ${port} not found`);
+			}
+		});
+	}
+
+	private verifyPort(port: number, reject: (reason?: any) => void) {
+		if (!port) {
+			let error = `Request to make a new center failed because of missing port.`;
+			this.logger.log1(error);
+			reject(error);
+		}
+	}
+}
\ No newline at end of file
diff --git a/src/Client/ClientSessionManager.ts b/src/Client/ClientSessionManager.ts
index c007c34..04cc8bd 100644
--- a/src/Client/ClientSessionManager.ts
+++ b/src/Client/ClientSessionManager.ts
@@ -1,52 +1,24 @@
 import EventEmitter from "events";
 import fs from "fs";
-import {Client} from "./Client";
 import {Job} from "../Job/Job";
 import Logger from "../Logger";
-import SessionManager from "../SessionManager";
+import {SessionManager} from "../SessionManager";
 import {SmppSession} from "../SmppSession";
+import {Client} from "./Client";
 
 const CLIENT_SESSIONS_FILE: string = process.env.CLIENT_SESSIONS_FILE || "client_sessions.json";
 
-export default class ClientSessionManager implements SessionManager {
-	sessionId: number;
-	sessions: Client[];
+export default class ClientSessionManager extends SessionManager {
+	sessionId: number = 0;
+	sessions: Client[] = [];
+	// Identifier is used in websockets to identify the type of session this manager manages
 	identifier: string = "client";
-	private readonly logger: any;
-	readonly SESSION_ADDED_EVENT: string = "SESSION ADDED";
-	private readonly eventEmitter: EventEmitter = new EventEmitter();
+	readonly logger: Logger = new Logger("ClientSessionManager");
+	readonly eventEmitter: EventEmitter = new EventEmitter();
 
 	constructor() {
-		this.sessionId = 0;
-		this.sessions = [];
-		this.logger = new Logger("ClientSessionManager");
-	}
-
-	on(event: string, listener: (...args: any[]) => void): void {
-        this.eventEmitter.on(event, listener);
-    }
-
-	getSessions(): Promise<SmppSession[]> {
-        return new Promise<SmppSession[]>(resolve => {
-			resolve(this.sessions);
-        });
-    }
-
-	addSession(session: SmppSession): Promise<void> {
-		return new Promise<void>((resolve, reject) => {
-			this.logger.log1(`Adding session with id ${session.getId()}`);
-			this.sessions.push(session as Client);
-			this.eventEmitter.emit(this.SESSION_ADDED_EVENT, session.getId());
-			resolve();
-		});
-	}
-
-	removeSession(session: SmppSession): Promise<void> {
-		return new Promise<void>((resolve, reject) => {
-			this.logger.log1(`Removing session with id ${session.getId()}`);
-			this.sessions = this.sessions.filter(s => s.getId() !== session.getId());
-			resolve();
-		});
+		super();
+		// super.eventEmitter.on(super.SESSION_ADDED_EVENT, (session: SmppSession) => this.eventEmitter.emit(this.SESSION_ADDED_EVENT, session));
 	}
 
 	createSession(url: string, username: string, password: string): Promise<SmppSession> {
@@ -54,7 +26,8 @@ export default class ClientSessionManager implements SessionManager {
 			this.logger.log1(`Creating session with url ${url}`);
 			this.getSessionByUrl(url).then(s => {
 				resolve(s);
-			}, err => {});
+			}, err => {
+			});
 			this.verifyUrl(url, reject);
 			this.verifyUsername(username, reject);
 			this.verifyPassword(password, reject);
@@ -66,24 +39,10 @@ export default class ClientSessionManager implements SessionManager {
 		});
 	}
 
-	getSession(id: number): Promise<SmppSession> {
-		return new Promise<SmppSession>((resolve, reject) => {
-			this.logger.log1(`Looking for session with id ${id}...`);
-			let session: SmppSession | undefined = this.sessions.find(s => s.getId() === id);
-			if (session) {
-				this.logger.log1(`Found session with id ${id}`);
-				resolve(session);
-			} else {
-				this.logger.log1(`Session with id ${id} not found`);
-				reject(`Session with id ${id} not found`);
-			}
-		});
-	}
-
 	getSessionByUrl(url: string): Promise<SmppSession> {
 		return new Promise<SmppSession>((resolve, reject) => {
 			this.logger.log1(`Looking for session with url ${url}...`);
-			let session: SmppSession | undefined = this.sessions.find(s => s.getUrl() === url);
+			let session: SmppSession | undefined = this.sessions.find((s: Client) => s.getUrl() === url);
 			if (session) {
 				this.logger.log1(`Found session with url ${url}`);
 				resolve(session);
@@ -94,13 +53,6 @@ export default class ClientSessionManager implements SessionManager {
 		});
 	}
 
-	serialize(): object {
-		this.logger.log1(`Serializing ${this.sessions.length} clients`)
-		return this.sessions.map((session: SmppSession) => {
-			return session.serialize();
-		});
-	}
-
 	setup(): void {
 		try {
 			this.logger.log1(`Loading clients from ${CLIENT_SESSIONS_FILE}`)
@@ -131,20 +83,4 @@ export default class ClientSessionManager implements SessionManager {
 			reject(error);
 		}
 	}
-
-	private verifyUsername(username: string, reject: (reason?: any) => void) {
-		if (!username) {
-			let error = `Request to make a new client failed because of missing username.`;
-			this.logger.log1(error);
-			reject(error);
-		}
-	}
-
-	private verifyPassword(password: string, reject: (reason?: any) => void) {
-		if (!password) {
-			let error = `Request to make a new client failed because of missing password.`;
-			this.logger.log1(error);
-			reject(error);
-		}
-	}
 }
\ No newline at end of file
diff --git a/src/SessionManager.ts b/src/SessionManager.ts
index df838a4..3965382 100644
--- a/src/SessionManager.ts
+++ b/src/SessionManager.ts
@@ -1,26 +1,80 @@
+import EventEmitter from "events";
+import Logger from "./Logger";
 import {SmppSession} from "./SmppSession";
 
-export default interface SessionManager {
-	sessions: SmppSession[];
-	sessionId: number;
-	identifier: string;
-	readonly SESSION_ADDED_EVENT: string;
+export abstract class SessionManager {
+	abstract sessions: SmppSession[];
+	abstract sessionId: number;
+	abstract identifier: string;
+	readonly SESSION_ADDED_EVENT: string = "SESSION ADDED";
+	readonly logger: Logger = new Logger("SessionManager");
+	readonly eventEmitter: EventEmitter = new EventEmitter();
 
-	addSession(session: SmppSession): Promise<void>;
+	addSession(session: SmppSession): Promise<void> {
+		return new Promise<void>((resolve, reject) => {
+			this.logger.log1(`Adding session with id ${session.getId()}`);
+			this.sessions.push(session);
+			this.eventEmitter.emit(this.SESSION_ADDED_EVENT, session.getId());
+			resolve();
+		});
+	}
 
-	removeSession(session: SmppSession): Promise<void>;
+	on(event: string, listener: (...args: any[]) => void): void {
+        this.eventEmitter.on(event, listener);
+    }
 
-	createSession(...args: any[]): Promise<SmppSession>;
+	getSessions(): Promise<SmppSession[]> {
+		return Promise.resolve(this.sessions);
+    }
 
-	getSession(id: number): Promise<SmppSession>;
+	removeSession(session: SmppSession): Promise<void> {
+		return new Promise<void>((resolve, reject) => {
+			this.logger.log1(`Removing session with id ${session.getId()}`);
+			this.sessions = this.sessions.filter(s => s.getId() !== session.getId());
+			resolve();
+		});
+	}
 
-	getSessions(): Promise<SmppSession[]>;
+	getSession(id: number): Promise<SmppSession> {
+		return new Promise<SmppSession>((resolve, reject) => {
+			this.logger.log1(`Looking for session with id ${id}...`);
+			let session: SmppSession | undefined = this.sessions.find(s => s.getId() === id);
+			if (session) {
+				this.logger.log1(`Found session with id ${id}`);
+				resolve(session);
+			} else {
+				this.logger.log1(`Session with id ${id} not found`);
+				reject(`Session with id ${id} not found`);
+			}
+		});
+	}
 
-	serialize(): object;
+	serialize(): object {
+		this.logger.log1(`Serializing ${this.sessions.length} clients`)
+		return this.sessions.map((session: SmppSession) => {
+			return session.serialize();
+		});
+	}
 
-	cleanup(): void;
+	// TODO: Maybe find a way to include write and read to file here too (instead of child classes)
 
-	setup(): void;
+	verifyUsername(username: string, reject: (reason?: any) => void) {
+		if (!username) {
+			let error = `Request to make a new client failed because of missing username.`;
+			this.logger.log1(error);
+			reject(error);
+		}
+	}
 
-	on(event: string, listener: (...args: any[]) => void): void;
+	verifyPassword(password: string, reject: (reason?: any) => void) {
+		if (!password) {
+			let error = `Request to make a new client failed because of missing password.`;
+			this.logger.log1(error);
+			reject(error);
+		}
+	}
+
+	abstract cleanup(): void;
+
+	abstract setup(): void;
 }
\ No newline at end of file
diff --git a/src/WS/ClientSet.ts b/src/WS/ClientSet.ts
index f7138d9..34cf925 100644
--- a/src/WS/ClientSet.ts
+++ b/src/WS/ClientSet.ts
@@ -1,5 +1,5 @@
 import Logger from "../Logger";
-import SessionManager from "../SessionManager";
+import {SessionManager} from "../SessionManager";
 import {SmppSession} from "../SmppSession";
 
 export class ClientSet {
diff --git a/src/WS/WSServer.ts b/src/WS/WSServer.ts
index 2d0498e..82b220e 100644
--- a/src/WS/WSServer.ts
+++ b/src/WS/WSServer.ts
@@ -1,6 +1,7 @@
 import Logger from "../Logger";
-import SessionManager from "../SessionManager";
+import {SessionManager} from "../SessionManager";
 import {ClientSet} from "./ClientSet";
+
 const WebSocket = require("ws");
 
 const WS_SERVER_PORT: number = Number(process.env.WS_SERVER_PORT) || 8191;
diff --git a/src/main.ts b/src/main.ts
index edf2c3d..6d8ea4d 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -3,7 +3,6 @@ import {Client} from "./Client/Client";
 import ClientSessionManager from "./Client/ClientSessionManager";
 import {Job} from "./Job/Job";
 import Logger from "./Logger";
-import {WSServer} from "./WS/WSServer";
 
 const smpp = require("smpp");
 const fs = require("fs");
@@ -19,7 +18,6 @@ const {PDU} = require("smpp");
 const app = express();
 
 const SERVER_PORT: number = Number(process.env.SERVER_PORT) || 8190;
-const CENTER_SESSIONS_FILE: string = process.env.CENTER_SESSIONS_FILE || "center_sessions.json";
 const MESSAGE_SEND_UPDATE_DELAY: number = Number(process.env.MESSAGE_SEND_UPDATE_DELAY) || 500;
 
 // TODO: Add support for encodings