For the past 6 months I've been having an issue, where often an SMS sent from a specific number just never gets through. I'll call it ProblemNumber.

Today, the owner of ProblemNumber said they'd sent me an SMS. It didn't arrive, they said they'll send another, which did not arrive either. I checked the database (el-v1.db) and didn't find either of those two messages.

Now, I have access to a system that can send SMS messages so that the recipient sees it as arriving from a sender I choose, so I sent a few messages with different senders to my own phone through that. The others arrived, but the ones sent as ProblemNumber didn't. This would indicate that the problem is most certainly in my own phone, and not in that of the owner of ProblemNumber.

I've vacuumed the database and done the test again, to no avail. A moment ago I deleted the whole database, but I still can't receive SMS messages from ProblemNumber.

I'm on CSSU 21.2011.38-1Tmaemo9.1. I have no SMS blacklist of any sort installed, and all my SMS messages to ProblemNumber have always gone through. Any ideas where to look next?

yeah, problem with his carrier - did you try to recieve an sms from that number on a second phone?
could also be a problem with your carrier, or even between two carriers

Same carrier on both subscribers, me and ProblemNumber. I contacted the carrier before posting here, they said they couldn't see anything wrong with my subscription, but re-initialized it just in case. That didn't change anything. The main reason I called them was to ask whether the messages sent from ProblemNumber to me were visible on their logs, but they said they can't access the logs like that. Privacy policy I suppose.

As I said, SMS messages with ProblemNumber as sender, whether from that phone or the system I mentioned, do not come through to me. If the problem is with the other phone, the latter test should've worked.

Now that I got home, I'll try this on my secondary N900.

Just saying, I have seen sms not arriving before, but not constantly, and not from a specific number only. It can happen for many reasons, most would be carrier network. I guess for anyone to really debug this, they need to know the number

I have two N900s, primary N900-1 and secondary N900-2. I swapped my Saunalahti carrier SIM to N900-2 and put a DNA carrier SIM to N900-1, and asked ProblemNumber to send an SMS to both. Result?
N900-1 with DNA SIM received nothing.
N900-2 with Saunalahti SIM received the SMS.

So, from this I'd deduce the problem lies in in N900-1, since it does not receive SMS from that one number with either SIM card.
I'll try cloning N900-1 to N900-2 and see what happens...

I'm not entirely sure how much of a proper cloning process it is to take an image backup of N900-1 with backupmenu and restore it to N900-2, but after this N900-2 still receives the test SMS while N900-1 does not.

Unfortunately, while the simple solution would be to switch to using N900-2, the two winters it spent in my car have debilitated it somewhat. Compared to N900-1...
- the indicator LED is dimmer
- experiences some graphical glitches
- generally feels slower
- cellular network & wifi reception is significantly weaker
- GPS accuracy is poor (one route with both phones recording simultaneously, N900-2 on the left)

I guess I could just use the N900-2 for a few days, flash N900-1, test SMS, restore backup to it, etc...but I would really like to find out the cause of this.

Maybe the carrie blocked the number receive.

make a test send from a website. try with http://mfreesms.com