mc8781 (881u) Voice activating - Access denied.

[Bayar]

Hi, who could suggest or explain the problem with Sierra Aircard mc8781 (same 881U) during voice activating process? Here I have active Dongle, Internet connection, card data:
Model : MC8781
IMEI : 3566850108xxxxx
Serial NR. : D353557145xxxxx
Firmware : F1_2_3_15AP
Voice feature : disabled
SIM Lock status : unlocked
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Activating voice for SierraWireless MC8781 ...
access denied !
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Same story for two aircards. Any ideas? Thanks!

[Vincentas]

Could you write your username or dongle serial number? Then I would check, why you may receive this error.