Seems, some Lumia 730 users are facing issues with their devices , when they try to dial a number or end a call. The device freezes and won’t respond and seems the issue is with Mobile+Sim settings. There is a thread over Microsoft discussions, where many have voiced their issue.
Now, some of these users have reached to us and we certainly want to help them. Microsoft moderators have offered solutions which are generic like soft reset, hard reset or using Nokia software recovery tool, but seems the issue still comes back.
One user has solved this issue by putting manual APN settings and disabling Dual-Sim settings.
SameerVarma replied on
I put manual settings of apn in my phone and turned off the dual call sim settings in network +. Its been 6 days with no hanging issues. Please make sure both settings are fine. Hope to see a positive reply from you.
May be the above workaround helps some. Anyways, here hoping that Microsoft fixes it with upcoming firmware update.