Fix the issue of dialing 8 or more digits
struct ast_channel *c
from sub->parent
whose type is brcm_pvt
not acting as expected, the ast_channel_exten_set(c, p->ext)
seems handled with some wrong memory address that leads to the issue.
Using the ast_copy_string
instead to set the sub->parent->ext
and sub->parent->context
directly, which will be used by brcm_new
(line 1918).