TDMA (AT&T Wireless): I was able to get wireless service until I passed the intersection with Mud Mountain Road. There is no service between here and Greenwater. Service is fairly continuous from Greenwater to Cayuse Pass. If you're going to Sunrise, I was able to get service up to Sunrise Point. I could not get a signal at Sunrise itself, but try taking your phone up to the top of the ridge. Service is spotty between Cayuse Pass and Chinook Pass. There is no service anywhere along SR 123 south of Cayuse Pass, including Ohannepecosh. If you continue to U.S. 12 and head toward Packwood, you will find spotty service along the highway until you get into town. So, it might be possible to use your phone on trails along SR 410 (Greenwater Lakes, Noble Knob) and possibly in the Sunrise area as long as you are up high (Burroughs Mountain, Mt. Fremont, Sourdough Ridge, Grand Park) and not down low (Berkeley Park). If you're travelling to the northwest corner of the park (Carbon River or Mowich Lake), I was able to get a signal on SR 165 until just before the bridge over the gorge. No service is available at Fairfax, the Carbon River Ranger Station or anywhere along the Carbon River Road. I thought I got a signal at Ipsut Creek Campground (end of the road), but I may have been imagining things. CDMA (Verizon Wireless): About the same, except there was service most of the way between Enumclaw and Greenwater (with some dead spots along the way). Driving on the road to Mowich Lake, I was able to get a signal, but several attempts to make a call did not go through. You may not be able to use your phone beyond Wilkeson. Location Tested Service When Tested Result Comments Sunrise-area trails (Silver Forest, Sourdough Ridge, and Dege Peak) AT&T Wireless (TDMA) 10/3/1999 Service Available--usually Tested at Sunrise, the official end of the Silver Forest trail, at a few points along Sourdough Ridge, and at Dege Peak. Service is spotty, as the cellular towers are northeast of the ridge, and Sunrise (and most people) are on the south side of the ridge. I found I was more likely to get a signal by moving away from the ridge (Silver Forest) or to spots on top of the ridge (such as Dege Peak) Crystal Lakes AT&T Wireless (TDMA) 7/8/2000 Service Available Tested at trailhead, near the junction with the Crystal Peak trail, at Lower Crystal Lake and at Upper Crystal Lake. Verizon Wireless (CDMA) 7/11/2004 Service Available in most areas Tested at trailhead, at junction with trail to Crystal Peak, and at both lower and upper lakes. Signal was very weak at the upper lake--several attempts to make a call were unsuccessful. I was able to successfully make a call from along the trail between the upper and lower lakes. I was also able to successfully receive a call from the first view of Rainier along the trail. Grand Park via FS Road 73, Lake Eleanor AT&T Wireless (TDMA) 8/18/2000 Service Available at Grand Park--BARELY Tested at trailhead, at Lake Eleanor, at the first big meadow south of Lake Eleanor (your first view of Rainier hiking in), at the north end of Grand Park, at the "silver forest" (grove of trees burned by a forest fire), and at the junction of the Grand Park and Northern Loop trails. Service is extremely spotty in Grand Park. Expect to have difficulties making a phone call from here. Summerland AT&T Wireless (TDMA) 8/26/2000, 7/28/2001, and 7/27/2003 Service Available Tested at crossing of Fryingpan Creek, near the backcountry shelter at Summerland, and on a ridge between Summerland and Panhandle Gap. Signal appeared to be barely adequate. Tested at trailhead on 8/5/2001--good signal there. I was also able to successfully make a call from outside the shelter at Summerland. Verizon Wireless (CDMA) 7/31/2004 Service Available Tested at trailhead, crossing of Fryingpan Creek, near the backcountry shelter at Summerland, and at Panhandle Gap. The signal was weak, but I was able to successfully make calls from Summerland and Panhandle Gap. Burroughs Mountain AT&T Wireless (TDMA) 9/23/2000, 9/9/2001 and 9/21/2003 Service Available (???) Tested in front of the flagpole at Sunrise, at overlook of Emmons Glacier, at the trail junction on First Burroughs Mountain, near the top of Second Burroughs Mountain, at the junction with the trail to Third Burroughs Mountain, at a couple of spots near the bottom between Second and Third Burroughs Mountain, on top of Third Burroughs Mountain, at Frozen Lake, and at the junction with the Huckleberry Creek trail. The signal was fairly good on top of Burroughs Mountain (all three peaks), but weaker at Frozen Lake. I did find a dead spot on top of Second Burroughs Mountain, so you may need to move around a little to get a signal. An attempt to make a call from the top of First Burroughs Mountain resulted in a fast busy signal. Verizon Wireless (CDMA) 9/7/2004 Service Available Tested in parking lot at Sunrise, near Emmons Overlook, at First Burroughs (trail junction), Second Burroughs, Third Burroughs, Frozen Lake, and on the ridge above Sunrise. I was able to successfully make calls from First, Second, and Third Burroughs and on the ridge above Sunrise, but you will need to be patient--it takes some time for the call to go through, and you may need to try more than once. Service was not available at Sunrise (go up on the ridge or move away from it) or Emmons Overlook. Noble Knob AT&T Wireless (TDMA) 7/14/2001 Service Available in some areas Tested at Corral Pass (trailhead), at junction with Deep Creek trail, at junction with Dalles Ridge trail, at junction with trails to Lake George and Lost Lake, and on the south slope of Noble Knob. I was not able to get service at Corral Pass because it is surrounded by small hills that block reception. Otherwise, since most of the trail is high on a ridge, it should be possible to get a decent signal in most areas Glacier Basin AT&T Wireless (TDMA) 8/5/2001 Spotty Service Available in some areas Tested at White River Campground (trailhead), at the junction with the trail to Emmons Glacier Overlook, at the junction with the trail to Burroughs Mountain, and near the campsite at Glacier Basin. The signal was weak where there was a signal at all. I was not able to get a signal at the junction with the trail to Burroughs Mountain. Others with me also had phones, and I think one was able to make a call from Glacier Basin itself. Sheep Lake/Sourdough Gap AT&T Wireless (TDMA) 8/25/2001 Service Available from Sourdough Gap north Tested at Tipsoo Lake, near Chinook Pass, at junction with abandoned trail to Deadwood Lakes, at Sheep Lake, at a couple of spots between Sheep Lake and Sourdough Gap, north of Sourdough Gap, at the junction with the trail to Crystal Lakes, and at a couple of spots above Upper Crystal Lake. A weak signal is available immediately south of Sourdough Gap, and there's a stronger signal north of the gap. No service is available at Sheep Lake, Chinook Pass, or Tipsoo Lake. Carbon Glacier Viewpoint AT&T Wireless (TDMA) 6/22/2002 Service Available at Ipsut Creek (?????) Tested at Ipsut Creek Campground (trailhead), at lower crossing of Carbon River, at upper crossing of Carbon River, and at the viewpoint. The signal I got at the trailhead may have been a figment of my imagination. Deadwood Lakes AT&T Wireless (TDMA) 9/27/2003 Service Available in some areas Tested at a couple of spots at the gap between the Pacific Crest Trail and Deadwood Lakes. I was able to successfully make a call from one of these spots. This trail is near the trail to Sheep Lake and Sourdough Gap (see above). Spray Park Verizon Wireless (CDMA) 9/13/2008 Service Probably Not Available Tested at trailhead and at several points within Spray Park (up to "The Top" at 6,400 feet). While I was able to get a signal, attempts to make a call did not go through.