<ion-tab [root]="tab5Root" tabIcon="call" (ionSelect)="call()" ></ion-tab> 

<ion-tab  tabIcon="call" (ionSelect)="call()" ></ion-tab> 

import { NavController, NavParams,ModalController,ViewController,Tabs } from 'ionic-angular'; 

constructor(public navCtrl: NavController, public navParams: NavParams,<span style="color:#ff0000;">public modalCtrl: ModalController,</span>public viewCtrl: ViewController) { 
 } 

call(){ 
 let modal = this.modalCtrl.create(CallModalPage); 
 modal.present(); 
}