When using Dual SIM and ALLOW CELLULAR DATA SWITCHING is enabled and DATA ROAMING is ON for both SIMs, at what point, either by signal strength, usable signal or some algorithm, will a data session switch from Primary Carrier to secondary carrier?

I did not come across an Apple Article that provided detailed information about the specific algorithms or criteria used to determine when to switch between primary and secondary SIM cards for cellular data. Howeverthere are a few general insights into how this process typically works in dual SIM smartphones.

1. In most cases, the phone will prioritize the SIM card with the stronger signal for data connectivity. If the primary SIM has a stronger signal than the secondary SIM, it will be used for data. However, if the primary SIM's signal is weak or non-existent, the phone may attempt to switch to the secondary SIM if it has a stronger signal.
2. It's not just about signal strength but also the quality of the signal. The phone may consider factors such as network congestion, signal stability, and data speed when deciding which SIM to use. Even if the primary SIM has a slightly stronger signal, the phone may switch to the secondary SIM if it can provide a more reliable and faster data connection.
3. Data roaming settings also play a role. If data roaming is enabled for both SIM cards, the phone should be more likely to switch to the secondary SIM if the primary SIM is unable to provide data connectivity. However, the exact behavior may vary depending on the phone's firmware and settings.
4. In some cases, users may need to manually switch between SIM cards if they want to ensure a specific SIM is used for data. While automatic switching is convenient, there may be situations where the user's preference differs from the phone's automatic selection.