hi jeff 🙂
3gpp TS 22811-720 6.12
6.12 Network selection in border areas
A problem exists for mobile users when commuting across national borders. Whilst manual network selection may be used to ensure that the user can select the HPLMN / EHPLMN, many users use Automatic Selection mode; and the ME is only permitted to select PLMNs of a higher priority within the same country in automatic mode. This leads to the situation that, having crossed back into its home country and within HPLMN coverage, an ME might remain camped on the VPLMN in the adjacent territory.
As a consequence, the user will be charged international roaming rates for all calls made or received until such time as he either
(a) moves out of VPLMN coverage or
(b) manually selects the HPLMN.
Please have a look to this thread :
and thanks again paraHO 🙂