I can’t say for sure why the ads have two phone numbers, although you are right that, especially in the west, local service for many of the independent phone companies was limited to a single town. However, in 1901 many people were also able to telephone surprisingly far distances, for example, the extract below reports that at the end of 1899 telephone communication had been established between Seattle and San Diego.
No matter what their regular service area, most of the telephone companies also had lines set up for connecting to distant exchanges, although these weren’t in steady use. Setting up a really long distance call took a fair amount of logistics–you had to first call your local exchange to schedule the call. The local exchange then had to send telegrams to all the exchanges along the route instructing them to patch together a line–this of course was long before automatic exchanges, so all the links were plugged in by hand. And the sound quality over long distances was pretty poor, so you might have to yell to be heard, and there was likely a lot of scratchy line noise to contend with. Still, it was a pretty remarkable achievement for the time.
You might find the following extract interesting:
Flame, Electrcity and the Camera, George Iles, 1904.
Chapter XVII: The Telephone (pages 234-236)
At long distances the boon of conversation,–of receiving an instant reply to a question, has special value. A patient confers with his surgeon, a railroad president with his counsel, an investor with his broker, as if they stood face to face. Because of this new facility the railroads between New York and Chicago are suffering a noteworthy loss of business; their rapid trains are less in request than formerly. Principals and agents, clients and attorneys, now find it unecessary to travel a thousand miles that their voices may be accompanied by themselves. Experiments of promise have been made in relaying the telephone, so that, as in the case of the telegraph, a message may be sent to an indefinately great distance by means of local currents brought here and there into the line. The human voice may yet belt the earth, and this before many years are past.
It has been found possible to send several telephonic messages simultaneously over the same wire, either in one direction, or in opposite directions. Should these experiments issue in commercial success the telegraph will find its rival formidable indeed. In the hands of Dr. Lodge the telephone has been refined to thirty-fold its ordinary sensitiveness, in which form it is an unapproached means of revealing minute electric currents. To pass to the other extreme of telephonic capacity, Edison, in constructing his megaphone, enables an assembly of a thousand persons to hear an oration, an orchestra, or a chorus borne upon electric waves for a distance of a hundred miles and more. In services of a more every-day kind let us mark the good offices of the ordinary instrument.
The acute responsiveness of the ordinary telephone at first seemed a serious barrier to its use for long distances. In a range of miles its wire was liable to come into the neighbourhood of telegraphic, lighting, or power circuits, whose pulsations it reported all too faithfully. The difficulty lay in balancing each disturbance by an equal and opposite disturbance, which problem, a little at a time, has been duly solved. The first improvement was in making each line double, so as to discard the “earth,” borrowed from telegraphy, as the return half of the circuit. This greatly reduced many perturbing influences, and barred out others completely. Another and more decided betterment lay in making the two wires of a circuit cross each other, without touching, at every mile the upper wire exchanging its place with the lower wire. This plan provides effectual compensation for inductive intrusions, leaving to the engineer the simple question of furnishing better metallic conductors. This he has done, first, by using hard drawn copper wire instead of iron, and next, by employing this in a size which at the end of 1899 had reached .165 of an inch. Among the cities most distant from each other which, on December 31, 1899, were in telephonic communication were San Francisco and Boise City, 1309 miles apart; Boston and Montgomery, 1538 miles; Boston and Omaha, 1556; Seattle and San Diego, 1567; Boston and Kansas City, 1609; Boston and Duluth, 1652; and Boston and Little Rock, 1793 miles. In this last case the two wires which form the circuit weigh in all no less than 780 tons; this huge mass is to be exceeded by that of the line, 1859 miles in length, soon to connect New York with New Orleans.