New phone ignores sure signal

[psgm]

My sure signal has been registered and working for 2 years. I recently upgraded to a Iphone 5s (same phone number), but it doesn't seem interested in the sure signal, instead hunting around until it picks up the dodgy external signal. 

My old phone also did this for a while before favouring the sure signal.

Is there a way I can force the phone to use the sure signal? 

Any ideas greatfully received.

[AnnS · Accepted solution]

Hi @psgm

If the number is the main number on  the account, you will need to deregister the number wait 24 hours and reregister the number.

If the number is a secondary number on the account, you need to remove and readd the number.

Further info to help on the links below.

Sure Signal - Support

Sure Signal Troubleshooting Guide