Recently there have been changes to Vietnam mobile numbers by all Vietnamese mobile operators, changing all from being 11 digits, over to 10 digits as of 15th September 2018. The mobile operators will continue to allow use of the old 11 digit numbers until 14th September 2018, however after this time all old numbers will become invalid and as such calls and SMS to them will fail. From 15th November only the new 10 digit mobile numbers should be used.
World Text will continue to be able to handle SMS delivery for all valid mobile numbers in Vietnam, but please be aware that from 15th November all numbers should be replaced with the updated prefixes as indicated below.
| Network | Old prefix | New Prefix |
| Viettel | 84162 | 8432 |
| Viettel | 84163 | 8433 |
| Viettel | 84164 | 8434 |
| Viettel | 84165 | 8435 |
| Viettel | 84166 | 8436 |
| Viettel | 84167 | 8437 |
| Viettel | 84168 | 8438 |
| Viettel | 84169 | 8439 |
| Mobifone | 84120 | 8470 |
| Mobifone | 84121 | 8479 |
| Mobifone | 84122 | 8477 |
| Mobifone | 84126 | 8476 |
| Mobifone | 84128 | 8478 |
| VinaPhone | 84123 | 8483 |
| VinaPhone | 84124 | 8484 |
| VinaPhone | 84125 | 8485 |
| VinaPhone | 84127 | 8481 |
| VinaPhone | 84129 | 8482 |
| Vietnamobile | 84186 | 8456 |
| Vietnamobile | 84188 | 8458 |
| Gmobile | 84199 | 8459 |