uni-app
<view class="serve" @click="call()">联系客服</view>
WeChat applet
wx.makePhoneCall(Object object) | WeChat Open Documentation
<view class="serve" data-phone="15952011111" bindtap="call">联系客服</view>
call(e) {
wx.makePhoneCall({
phoneNumber: e.currentTarget.dataset.phone
})
}