Timer is not working inside service

Hi

I have the following 2 problems
1. my app need to call some number, soon after I receive SMS with the details (running as a service) , but as soon as the SMS is arriving the dial process begins and terminate, without finish the call (it is like you dial and cancel the call)
so i tried to overcome by adding timer (I tought maybe this is race problem)
and now second problem
2. timer is not working inside the service - getting error of force shuting my app

Can you help with first problem - so I will know why, and with solution (maybe the second problem is the solution)

here is the code

Sub SI_MessageReceived (From As String, Body As String)
MessageFrom1 = From
MessageBody1 = Body
Check_Arrived_SMS
End Sub

Sub Check_Arrived_SMS

StartActivity(PhoneCall.Call("0541234567"))

End Sub

-------Second problem - after trying to add timer ------
Sub SI_MessageReceived (From As String, Body As String)
MessageFrom1 = From
MessageBody1 = Body
Timer1.Enabled = True
End Sub

Sub Timer1_Tick

Timer1.Enabled = False
ToastMessageShow("Timer", False)
StartActivity(PhoneCall.Call("0541234567"))


End Sub