Develop Reference

Windows phone store Query

We have an app which is built in Windows phone 8 silver light framework. As windows 10 is coming and we are trying to upgrade this app to Windows phone 8.1.
Our only concern is can we keep both version of the app on store? i.e on store we should be able to upload two different build for WP8 and WP8.1.
Let me know if you guys have the answer

Yes you can have two different versions in the store. But my question is if you do have a Windows Phone 8 version of an application why do you need the 8.1 version too, where WP8 application would support both the versions?
You could have a look at this, in order to migrate your app into Universal apps.

ActivationPolicy="Replace" not working in Windows Phone 8.1

In Windows Phone 8.1 the default ActiovationPolicy changed from Replace to Resume.
I have a Windows Phone 8.1 Silverlight app and I want to use ActivationPolicy="Replace". Changing ActivationPolicy="Resume" to ActivationPolicy="Replace" does not work, the app still resumes.
I remember one video from build claiming that this should work, but is this really possible? If so, what is the way to make the app replace instead of resume?

Windows Phone 8.1 Silverlight apps always resume (http://social.msdn.microsoft.com/Forums/wpapps/en-US/caf0d79a-c55e-4046-afc1-86260c005205/activationpolicyreplace-not-working-in-windows-phone-81?forum=wpdevelop)

Make a phone call in Windows Phone 8.1

I'm writing a Universal App for Windows 8.1 / Windows Phone 8.1 that at some point displays a list of phone numbers. What I would like to do is allow the user to press one of these numbers and have the device call (or ask permission to call) that number if running on Windows Phone 8.1. I know this was previously possible in Windows Phone 8 by doing the following:
using Microsoft.Phone.Tasks;
PhoneCallTask phoneCallTask = new PhoneCallTask();
phoneCallTask.PhoneNumber = "2065550123";
phoneCallTask.DisplayName = "Gage";
phoneCallTask.Show();
NOTE: This code is wrapped in #if WINDOWS_PHONE_APP
However, when trying to import Microsoft.Phone.Tasks, Visual Studio is unable to find the reference. I know that "ID_CAP_PHONEDIALER" had to be enabled in WMAppManifest.xml in Windows Phone 8, but this doesn't seem to be possible with the universal app model. I've been searching around for a solution but can't find a recent one that includes Windows Phone 8.1 (not Silverlight).
Is there any way to make a phone call from within a universal app? Or is it simply not possible at the moment?

In Windows Phone 8.1, We can make phone call by "Windows.ApplicationModel.Calls.PhoneCallManager", just like this:
Windows.ApplicationModel
.Calls.PhoneCallManager
.ShowPhoneCallUI("phone number", "display name");

Detect OS version - Windows Phone 7 or Windows Phone 8?

I have an application for Windows Phone 7. I have created visual studio 2012 in windows 8 desktop. I am trying to use the application in Windows Phone 8 device also with some changes involved. How can I programmatically detect whether the device is Windows Phone 7 or Windows Phone 8?

Just as you would on any other platform with C#: Environment.OSVersion

You can use this toolkit to check the version of the phone:
http://mangopollo.codeplex.com/
bool IsWP8() : Returns if the phone running the application is a
Windows Phone 8
EDIT: If you don't want to use the whole toolkit here is how it checks it:
public static bool IsWP8 { get { return Environment.OSVersion.Version >= TargetedVersion; } }
private static Version TargetedVersion = new Version(8, 0);
Creds to original author.

You shouldn't need to.
Either it is a Windows Phone 7 app and will work on both Windows Phone 7 and Windows Phone 8 devices or it is a Windows Phone 8 application.
A Windows Phone 7 app running on Windows Phone 8 shouldn't be able to do anything that a Windows Phone 7 device shouldn't be able to do.

This article has some good strategies as well.
http://msdn.microsoft.com/en-us/library/windowsphone/develop/hh202996(v=vs.105).aspx
It is not just about run-time either, for example, your code may function one way on wp7 and another on wp8 depending on availability of an API. In this case a #define may the best way to go, because you really don't care what kind of device you are running on, but what SDK you were built against.

Programmatically Set APN Settings wp7

i started to devellop application to get setting system parameters of device automatically with windows phone 7
my problem is how can setting APN and proxy of the device programmatically( windows API or program c#) in windows phone 7 or windows phone 8
please if an expert in windows phone have an idea help me .
thanks :)

According to my knowledge there's no way to access such settings in WP7 but there's a hop in WP8
Check this link
http://msdn.microsoft.com/library/windowsphone/develop/ff626516(v=vs.105).aspx