You may need to explore this part of the 46xxsettings file as it may also be related with the length of your extensions.
## Country Code
## For United States the value is '1'
## Valid values 1 to 999. The default value is 1.
## J129 SIP R1.0.0.0 (or R1.1.0.0), J169/J179 SIP R1.5.0, J100 SIP R2.0.0.0 and later, J139 SIP R3.0.0.0 and later, J159 SIP R4.0.3.0 and later, J189 SIP R4.0.6.1 and later
## J169/J179 H.323 R6.7 and later, J159 and J189 H.323 R6.8.5 and later
## Avaya IX Workplace 3.1.2 and later; default is "".
## Avaya Vantage Connect Application SIP R1.0.0.1 and later; default is "".
## H1xx SIP R1.0 and later
## 96x1 H.323 R6.0 and later
## 96x1 SIP R6.0 and later
## 96x0 H.323 R1.0 and later
## 96x0 SIP R2.5 and later
## SET PHNCC 1
##
## Internal extension number length
## If your extension is 12345, your dial plan length is 5.
## On 96xx phones, the maximum extension length is 13.
## This value must match the extension length set on your
## call server.
## Valid values are 3-13. The default value is 5.
## J129 SIP R1.0.0.0 (or R1.1.0.0), J169/J179 SIP R1.5.0, J100 SIP R2.0.0.0 and later, J139 SIP R3.0.0.0 and later, J159 SIP R4.0.3.0 and later, J189 SIP R4.0.6.1 and later
## J169/J179 H.323 R6.7 and later, J159 and J189 H.323 R6.8.5 and later
## Avaya IX Workplace 3.1.2 and later; default is "".
## Avaya Vantage Connect Application SIP R1.0.0.1 and later; default is "".
## H1xx SIP R1.0 and later
## 96x1 H.323 R6.0 and later
## 96x1 SIP R6.0 and later
## 96x0 H.323 R1.0 and later
## 96x0 SIP R2.5 and later
## SET PHNDPLENGTH 5
##
## International access code
## For the United States, the value is 011.
## Valid values are 0 to 4 dialable characters (0-9,*,#). The default value is "011".
## This parameter is supported by:
## J129 SIP R1.0.0.0 (or R1.1.0.0), J169/J179 SIP R1.5.0, J100 SIP R2.0.0.0 and later, J139 SIP R3.0.0.0 and later, J159 SIP R4.0.3.0 and later, J189 SIP R4.0.6.1 and later
## J169/J179 H.323 R6.7 and later, J159 and J189 H.323 R6.8.5 and later
## Avaya IX Workplace 3.1.2 and later; default is "".
## Avaya Vantage Connect Application SIP R1.0.0.1 and later; default is "".
## H1xx SIP R1.0 and later
## 96x1 H.323 R6.0 and later
## 96x1 SIP R6.0 and later
## 96x0 H.323 R1.0 and later
## 96x0 SIP R2.5 and later
## SET PHNIC 011
##
## Long distance access code
## Valid values are 0 through 9 and empty string. The default value is 1.
## if no long distance access code is needed then SET PHNLD "".
## This parameter is supported by:
## J129 SIP R1.0.0.0 (or R1.1.0.0), J169/J179 SIP R1.5.0, J100 SIP R2.0.0.0 and later, J139 SIP R3.0.0.0 and later, J159 SIP R4.0.3.0 and later, J189 SIP R4.0.6.1 and later
## J169/J179 H.323 R6.7 and later, J159 and J189 H.323 R6.8.5 and later
## Avaya IX Workplace 3.1.2 and later; default is "".
## Avaya Vantage Connect Application SIP R1.0.0.1 and later; default is "".
## H1xx SIP R1.0 and later
## 96x1 H.323 R6.0 and later
## 96x1 SIP R6.0 and later
## 96x0 H.323 R1.0 and later
## 96x0 SIP R2.5 and later
## SET PHNLD 1
##
## National telephone number Length
## For example, 800-555-1111 has a length of 10.
## Valid values are 5-15. The default value is 10.
## This parameter is supported by:
## J129 SIP R1.0.0.0 (or R1.1.0.0), J169/J179 SIP R1.5.0, J100 SIP R2.0.0.0 and later, J139 SIP R3.0.0.0 and later, J159 SIP R4.0.3.0 and later, J189 SIP R4.0.6.1 and later
## J169/J179 H.323 R6.7 and later, J159 and J189 H.323 R6.8.5 and later
## Avaya IX Workplace 3.1.2 and later; default is "".
## Avaya Vantage Connect Application SIP R1.0.0.1 and later; default is "".
## H1xx SIP R1.0 and later
## 96x1 H.323 R6.0 and later
## 96x1 SIP R6.0 and later
## 96x0 H.323 R1.0 and later
## 96x0 SIP R2.5 and later
## SET PHNLDLENGTH 10
##
## Outside line access code
## The number you press to make an outside call.
## Valid values are 0 to 2 dialable characters (0-9, *, #). The default value is 9.
## This parameter is supported by:
## J129 SIP R1.0.0.0 (or R1.1.0.0), J169/J179 SIP R1.5.0, J100 SIP R2.0.0.0 and later, J139 SIP R3.0.0.0 and later, J159 SIP R4.0.3.0 and later, J189 SIP R4.0.6.1 and later
## J169/J179 H.323 R6.7 and later, J159 and J189 H.323 R6.8.5 and later
## Avaya IX Workplace 3.1.2 and later; default is "".
## Avaya Vantage Connect Application SIP R1.0.0.1 and later; default is "".
## H1xx SIP R1.0 and later
## 96x1 H.323 R6.0 and later
## 96x1 SIP R6.0 and later
## 96x0 H.323 R1.0 and later
## 96x0 SIP R2.5 and later
## SET PHNOL 9
##
## Add Outside line access code (specified in PHNOL) when dial string start with PHNOL.
## Value Operation
## 0 Do not add PHNOL when dial string start with PHNOL (Default)
## 1 Add PHNOL when dial string start with PHNOL
## Note: For customers who would like to have pre R6.6.3 PHNOL behavior then value 1 shall be set.
## This parameter is supported by:
## J169/J179 H.323 R6.8.2 and later, J159 and J189 H.323 R6.8.5 and later
## 96x1 H.323 R6.8.2 and later
## SET PHNOLADD 1