Question: Just pulled out an old SIM card and noticed it still has a signal but no balance - how to check my own number on du sim? all suggestions welcome except calling du customer care :))

haha . Looks like your old SIM didnt work. I think the SIM cards have a validity and after some time if they are not used they are disconnected. 

lucky you Mohammad. Not 100% sure, but to get your own du number, you may want to send an SMS to 9256 with the message getmymsisdn. I think it works even if you do not have a balance. 

Let me know how it goes