GPRS/EDGE issues after going out of coverage

Dear all

We are experiencing a strange issue in our Network .GSM -Huawei (No WCDMA.Data means GPRS/EDGE).

In some cases when customer goes out of coverage area (usually for a long time ) and comes back he is having no data coverage.

He has to power cycle his mobile . Then only the "E" or "G" Symbol appears. Even making a voice call is of no use .Not limited to MDN or CELL .

since it is not happening always it is very difficult to trace . But we know this issue exist in network .

Thanks in advance

Regards