[psychopomp1]

Hi,
Hope someone can shed light on this issue, its driving me nuts!! I have an unlocked iphone SE (purchased from Apple) which i was using without any problems in UK on the Virgin network (sim only). I'm currently in Qatar and put a Ooredoo network post-paid sim in the iphone but I find that if i try to make any call i get the 'call failed' error and the only way to fix this is by dialling *#31#. However after a few days or whenever i switch on and then re-start my iphone i get the error again and I have to dial *#31# again to enable outgoing calls. I'm guessing *#31# does something to the caller ID setting which btw is greyed out (but 'on') under settings>phone>show my caller ID.

I'm using the latest iOS , done 'reset network settings' and also 'reset all settings' but the error keeps coming back. I'm reluctant to do a full erase and restore as i would be unable to use the TalkTalk Business Talk2Go app from abroad after a full reset as this is linked to my UK Virgin number - the app gives me free unlimited calls to UK landline & mobile numbers over wifi and local 3G/4G network.

The Ooredoo sim card doesn't have this issue on a different handset (non iphone) so pretty sure its related to my iphone. Any idea on how to fix this without having to do a full erase and restore?
Thanks!