pls contact me (by) telephone no. 1231-1231　　 有冇錯？

pls contact me (by) telephone no. 1231-1231　　 有冇錯？

Bingo! 完全無錯.
如要雞蛋裡挑骨頭, 就是 number 的簡寫應是 No. (N 必需是capital letter.)

Please contact me by telephone at 1231-1231

講途徑用by
例如 by phone, by email, by fax

但講電話號碼用at
e.g. You can reach me at 1231-1231.

如有問題 請通知我 電話:1231-1231
please contact me should any problems arise on 1231-1231

OR simply
please contact me on 1231-1231

不過 by 都 ok 架啦!
please contact me by telephone on 1231-1231
(唔洗 no. )

use (via)
pls contact me (via) telephone no. 1231-1231