Texts not being sent - intermittent. Help!

[Anonymous]

I am a Pay Monthly 02 customer how has been having issues texting a select few numbers for the past 12 months or so.
The texts look like they have gone through on my side but sometimes they don't receive them. It's very intermittent, some days/weeks will be fine others nothing goes through. I've done everything suggested on help including checking the number isn't blocked, restarting the network, turn it off and on, wipe the sim card. But nothing.
I had a different sim and phone last year (still same number and network) and had these issues. I got a new phone in June with a new sim (again same number same network just needed a small one) so it can't be the sim card or the phone as I've had two ones.

I'm getting fed up of it if I'm honest. These select few are on different networks, they've checked their settings and everything's ok. I text them regularly- one of them is my boyfriend, so you can imagine why I'm getting fed up.

Any advice?

[MI5]

Statistically only 75% of text sent are actually delivered.
The more you send, the bigger the chance that you will get failures.
This is just down to old tech used in the GSM gateway for sms messaging.
Much better off using messaging apps like WhatsApp etc these days.

[Anonymous]

Hi, I am having exactly the same problem. However my signal is also dipping until I actually don't have any signal. Like you said, very annoying especially during the Christmas period. I think this is why I am also having problem with receiving texts due to my signal constantly dipping for prolonged periods of time. The message may send OK (or so I think) but the receiver does not receieve my texts and vice versa. Causing a lot of hassle!! Also an example yesterday I received a text at 23:30. When i checked the time stamp of the message it was sent at 20:30. Very confusing as i only receieved this text at 23:30. Happening all day today also!!

[MI5]

If you have a flaky signal you should switch the phone to 2g network only to prevent the phone from attempting to log on to the usually weaker 3G signal.