You may post ads in up to 5 different cities per week (you'll have to specify when you will be available in those cities).
From the provider advertising guidelines.
http://eccie.net/showthread.php?t=19227
Some of our Metro Locations have Provider Ad Subdivisions. (ex. Dallas/Fort Worth, 5 NE Texas Subdivisions, etc) You may post your weekly ad(once every 7 days) in as many subdivisions you would like within your 5 city allotment for the week…..however, you must be advertising availability for the geographic location you are advertising in….whether you will be traveling there from another city, have an incall in that town, or provide outcall appts to that area.