CORVALLIS (AP) — Thirteen years after Oregon added a second area code, the number of numbers available to phone customers in the new 541 area is running out.

State regulators are considering what to do when the numbers are exhausted, which is expected in 2011.

One good possibility is to follow the example set in the 503 area: Just add a new number, as 971 was made available in 2000 for new customers in the 503 area.

That’s the solution recommended by a consultant and the telephone industry. Customers would keep their numbers, but local calls would require 10-digit dialing, including the area code.

But the Public Utility Commission is looking for other suggestions as well, said spokesman Bob Valdez. It is holding a series of 18 public meetings beginning Thursday.

A decision is expected in the fall, with the changes taking effect in 2010.

All the options were weighed for how long they would last before another change is needed. Adding a new area code for new customers in the 541 area is forecast to be good for 24 years.

The other options:

* Break the 541 area into two sections. Most of central and eastern Oregon would maintain the 541 area code, while the western half of the state would add a new area code on top of the 541 code. This option would give customers only a six-year respite before additional changes were required.

* Expand the 971 area code to the entire state, a solution good for 11 to 15 years before a new solution would be needed.

* Split the Willamette Valley from central, eastern and southern Oregon. Give one of the two sections the 541 area code, and give the other a new number — and have those customers bear the cost of making the change in changing stationery, business cards and so forth. That option would be good for 20 years in one section, 29 years the other.

The commission plans open houses in August around the state.