01-05-2023 19:25
01-05-2023 20:10
Not sure where you are or where you are trying to call, but if they are chargeable calls, you may have a spend cap preventing them.
Some things to try:
1 - Reboot phone. (or toggle airplane mode).
2 - Manually search for a different network
4 - Check with O2 for any roaming bars.
5 - If in USA, see this USA - Roaming with O2
If you message O2 on Facebook (https://o2uk.co/O2CFB) , Twitter (https://o2uk.co/O2CTW) or Instagram (https://o2uk.co/O2CIG) , they should be able to help you with this.