Please Assist With Formula That Looks at First Number

[meppwc]

My column C represents a list of phone numbers that are all 5 digits long.
The list represents internal phone numbers of our company
For example - 43140 would be how you could call within the company where as 4 is the last number of the NXX and 3140 would represent the line.

What I want to do in column D is create a list of the full phone numbers for column C (NPA-NXX-LINE).
For example
If cell C2 is 43140, then D2 would be 314-694-3140

Column C also has numbers that start with 7 (72263 for example)
If cell C3 is 72263, then D3 would be 636-737-2263

The 5-digit TNs in column C always start with 4 or 7 and the needed result will always start with either 314-694 or 636-737

 

[njimack]

=lookup(left(c2)+0,{4,7},{"314-694","636-737"})&"-"&right(c2,4)

 

[Fluff]

How about
=IF(LEFT(C4,1)="4","314-694-"&RIGHT(C4,4),"636-737-"&RIGHT(C4,4))

 

[meppwc]

wow that worked perfectly............thanks so much